Evolution of English Textbook Content in China’s Higher Vocational Education: A Curriculum Standards Perspective

2.1 The Importance of Curriculum Standards and Their Relationship with Textbooks

In modern education systems, curriculum standards have become core policy instruments for ensuring educational quality, promoting educational equity, and guiding educational reform, with their importance widely recognized globally (Null 2023). As official definitions by national or authoritative educational bodies regarding the knowledge, skills, competency goals, and content for specific educational stages and subjects, curriculum standards not only provide a basic framework and expected goals for teaching activities but also constitute the basis for measuring educational effectiveness and implementing educational accountability (Eden et al. 2024). They are a concentrated reflection of national educational will and contemporary talent development philosophies, profoundly influencing the direction and quality of educational practices within a country or region (Luo 2023).

Among the various objects influenced by curriculum standards, textbooks undoubtedly occupy a critically important position. It is widely acknowledged internationally that textbooks are the primary carriers of curriculum standards and the most direct curriculum resource in teaching practice (Apple 2021). They transform abstract curriculum goals and content requirements into concrete learning materials and activity sequences usable by teachers and students, serving as a key bridge connecting the “intended curriculum” (represented by standards) and the “implemented curriculum” (what actually happens in the classroom) (Priestley et al. 2021). Therefore, whether textbooks can accurately and effectively embody the spirit and requirements of curriculum standards directly relates to the achievement of curriculum goals and the actual effect of educational reforms. The quality, structural arrangement, and value orientation of textbook content significantly shape students’ learning experiences and teachers’ pedagogical behaviors (Ye 2022).

Given this core relationship between curriculum standards and textbooks, the alignment, consistency, or fidelity between the two has naturally become a persistent focus of international research in curriculum and textbook studies (Priestley et al. 2022). A large body of international research investigates the extent to which textbook content reflects the requirements of corresponding curriculum standards across different countries and subject areas. However, research findings often reveal significant discrepancies or gaps between the “intended curriculum” and the “curriculum-in-the-textbook” (Schmidt et al. 2022). For instance, some studies find that textbook content may lag behind standard updates (Zhao et al. 2023), or inadequately reflects certain requirements of the standards, such as the cultivation of higher-order thinking skills or inquiry-based learning (Wang et al. 2024). The reasons attributed to this inconsistency are multi-faceted, including ambiguity in the standards themselves, discrepancies in interpretation by textbook authors or publishers, market factor interference, limitations of the textbook development cycle, and the lack of effective coordination and review mechanisms (Supriani et al. 2022). Consequently, empirical research on the consistency between curriculum standards and textbooks is crucial not only for diagnosing the on-the-ground implementation status of curriculum policies within specific educational systems but also for providing vital evidence to optimize curriculum standard design, improve textbook development processes, and enhance the effectiveness of curriculum implementation. Understanding the universality and specific manifestations of this consistency issue globally provides necessary international context for examining the specific situation in China within this study.

2.2 Theoretical Perspectives and Common Dimensions of Textbook Content Analysis

Textbook content analysis, as a core method in textbook research, aims to reveal the intrinsic characteristics and potential impacts of textbooks through systematic investigation (Smolarek and Luke 2023). Academia has developed methods and dimensions for analyzing textbook content from various theoretical perspectives. For example, based on linguistic theory, researchers often focus on vocabulary frequency and distribution, grammatical structure complexity, discourse types and cohesion devices, and language authenticity within textbooks (Flowerdew 2023). Grounded in Second Language Acquisition (SLA) theory, analysis frequently centers on the comprehensibility of language input, the design of output activities, methods of skills integration (such as the balance and combination of listening, speaking, reading, writing, and translation), and adherence to cognitive principles (like difficulty gradients) (Brown and Lee 2025). Sociocultural theory perspectives draw attention to the presentation of culture in textbooks (target language culture vs. native culture), the presence of stereotypes or biases, the cultivation of intercultural communication competence, and the transmission of hidden ideologies or values (Risager 2023). Instructional design theory guides researchers to examine task types (e.g., Pushed Output, TBLT), activity sequences, learner-centeredness, cognitive engagement levels, and technology integration within textbooks (Smith and González-Lloret 2021). Furthermore, for vocational education textbooks, analytical dimensions often require special attention to vocational elements, such as industry background knowledge, workplace scenario simulation, features of English for Specific Purposes (ESP), and the integration of professional qualities (Zeng 2024). Commonly used content analysis or evaluation frameworks in existing research (such as the classic checklists proposed by Cunningsworth, Hutchinson & Waters, which, though focused on evaluation, also encompass content analysis dimensions) often synthesize multiple perspectives mentioned above, providing a foundation for systematically evaluating and understanding textbooks (Tomlinson 2023). This study will build upon these theoretical perspectives and common analytical dimensions to construct a specific analysis framework tailored to its research objectives (see Section 3.4).

2.3 Related Research on the Development of HVE English Textbooks in China

Chinese scholars have accumulated considerable achievements in English textbook research, particularly in the fields of basic education and general higher education. Although research focusing on HVE English textbooks is increasingly growing, it exhibits certain focal characteristics. Existing research pays the most attention to the textbook compilation stage. A large volume of literature discusses the principles HVE English textbooks should follow (e.g., vocational relevance, practicality, applicability), core concepts (e.g., task-based teaching, needs analysis, industry-education integration), specific content selection (e.g., strategies for integrating industry English, development paths for school-based textbooks), and issues concerning the construction and integration of digital teaching resources (Wang et al. 2023; Yang 2023; Wei 2023). Secondly, textbook evaluation research constitutes another significant area. Scholars either adopt established international evaluation models or attempt to construct localized evaluation indicator systems to analyze various HVE English textbooks available on the market, examining their strengths, weaknesses, and alignment with curriculum standards. However, research also points out that current evaluation still faces challenges such as lack of unified standards and insufficient empirical evidence (Liu and Wen 2023; Jia 2022). Additionally, textbook usage research has received some attention. Related discussions involve how teachers understand and conduct “secondary development” of textbooks, how specific teaching strategies (e.g., multimedia assistance, ESP teaching models) can be effectively combined with textbook content, and how to better meet students’ usage needs. Nevertheless, research focusing on learners’ autonomous usage strategies remains relatively weak (Ren et al. 2023). Meanwhile, research at the textbook publishing level has explored the relevant policy environment, market status quo and problems, and trends in textbook publishing format transformation against the backdrop of the digital era (Li 2021).

Despite these multi-faceted research accumulations, as identified in the author’s prior literature review, significant gaps persist in the existing research: first, there is a scarcity of high-level research outcomes, and research efforts are scattered; second, research methodologies are often singular, lacking large-scale, long-term empirical analysis; third, research content lacks systematicity, particularly the absence of in-depth studies that systematically and diachronically link the evolution of textbook content with the successive reforms of curriculum standards. Most studies remain synchronic analyses of textbooks from a specific period or type, failing to clearly and comprehensively delineate the dynamic developmental trajectory of Chinese HVE English textbooks under the guidance of national curriculum policies and its underlying logic. Therefore, building upon the existing research foundation, this study focuses on “curriculum standard reform” as the key variable. Employing a combination of historical research and content analysis methods, it undertakes a systematic diachronic investigation of the content evolution of HVE public English textbooks over three decades. This approach aims to fill the gaps in existing research regarding historical depth and systematic correlation analysis, thereby providing a more solid research foundation for comprehensively understanding and promoting the high-quality development of HVE English textbooks in the new era.

3.1 Research Methods

This study comprehensively employs the following research methods:

1. Literature Review Method: Systematically collecting and studying successive HVE public English curriculum standard documents, relevant national education policy documents, academic literature on textbook theory and content analysis, and existing research findings on HVE English textbooks. This provides the theoretical basis, policy context, and frame of reference for the current study.

2. Historical Research Method: Following a chronological thread, this method is used to delineate the promulgation background, core concepts, and main requirements of the four key curriculum standards since 1993, as well as the macro-environment for HVE and English language teaching development in corresponding periods. This constructs the diachronic analytical framework for textbook content evolution.

3. Content Analysis Method: This serves as the core method of the study. By constructing a systematic content analysis framework (see Section 3.4), representative textbook samples from different periods are subject to in-depth, detailed textual analysis to extract key content features, identify changing trends, and perform necessary quantitative statistics.

4. Comparative Research Method: This method involves, on one hand, diachronic comparison to analyze the main similarities and differences in textbook content across different standard periods, revealing evolutionary patterns. On the other hand, it involves synchronic comparison between textbook content from a specific period and the requirements of the corresponding curriculum standard to examine the degree of textbook responsiveness and potential gaps.

5. Case Study Method: Representative textbooks selected from each period are analyzed in depth as specific cases. This allows for a detailed presentation of the typical features and nuances of textbook content during that era, enhancing the persuasiveness of the research.

3.2 Definition of Research Period and Basis for Periodization

The temporal scope of this study is primarily set from 1993 to 2023, covering the four key reforms experienced by the curriculum standards for public English in Chinese HVE. The periodization strictly adheres to the official curriculum standard documents promulgated by national (or relevant Ministry of Education departments/steering committees) authorities that have exerted widespread influence:

Phase 1: Foundational and Standardization Exploration Period (Approx. 1993 – 1999): Starting with the promulgation of the “Basic Requirements for General Higher Specialized English Curriculum Teaching” by SEC in 1993.

Phase 2: Quality-Oriented Education and Knowledge Update Period (Approx. 2000 – 2011): Marked by the promulgation of the “Basic Requirements for English Curriculum Teaching in Higher Vocational and Higher Specialized Education (Trial)” by the Higher Education Department, MOE, in 2000.

Phase 3: Vocational Competence Strengthening Period (Approx. 2012 – 2020): Demarcated by the promulgation of the “Teaching Requirements for Higher Vocational Education English Curriculum” by the Advisory Committee of Foreign Language Teaching in Vocational Education, MOE, in 2012.

Phase 4: Nurturing Function and Modernization Orientation Period (Approx. 2021 – Present): Commencing with the promulgation of the “Curriculum Standard for Higher Vocational Education Specialty English Courses (2021 Edition)” by the Department of Vocational and Adult Education, MOE, in 2021.

This periodization method aims to clearly correspond the evolution of textbook content with the reform nodes of the curriculum standards, facilitating the examination of the interactive relationship between the two.

3.3 Textbook Sample Selection

To ensure the representativeness and validity of the research, this study employs a purposeful sampling strategy to select textbook samples. The main selection criteria include:

1. Authority and Representativeness: Priority is given to public English textbook series for HVE (specialty level) that were widely used, influential during the corresponding historical period, and particularly those listed as “National Planning Textbooks”.

2. Diachronic Coverage: Ensuring that at least 1 – 2 representative textbook series (including main coursebooks and important supplementary components) are selected for analysis from each of the four defined periods.

3. Accessibility: The selected textbook samples must be obtainable by the researcher in physical or reliable digital format for detailed analysis.

3.4 Content Analysis Framework

Based on the literature review and research objectives, this study constructs a content analysis framework comprising the following main dimensions to systematically examine the evolution of textbook content (see Table 1):

3.5 Analysis Procedure

The analysis procedure of this study will unfold systematically and stage-by-stage, following the principles of combining systematicity with a diachronic perspective. Firstly, the research will involve in-depth study and interpretation of the curriculum standard documents from the four key historical periods to precisely extract the core requirements, reform focuses, and expected talent cultivation goals for each stage, serving as the benchmark and reference point for subsequent analysis. On this basis, detailed coding sheets or analysis guides will be developed according to the content analysis framework constructed in Section 3.4, ensuring the systematicity and operability of the textbook content analysis. Secondly, the core phase involves meticulous textual reading and content coding of the representative textbook samples selected for each period (see Section 3.3). Key characteristic manifestations and relevant data across different analytical dimensions will be systematically recorded according to the framework, based on which the overall landscape and characteristics of textbook content for each historical period will be summarized. Subsequently, comparative research methods will be employed. On one hand, diachronic comparison across periods will be conducted to delineate the evolutionary paths, key change points, and development trends for each content dimension over the time series. On the other hand, the characteristics of textbook content will be synchronically compared against the requirements of the corresponding curriculum standard for that period. Furthermore, the analysis will focus on identifying the response patterns of textbook content evolution to curriculum standard reforms (e.g., lagging, synchronous, or exceeding) and explore the underlying reasons in conjunction with historical context and documentary evidence. Finally, through comprehensive integration and in-depth interpretation of the analysis results from the preceding steps, this study aims to ultimately form a systematic understanding of the patterns, characteristics, and the interactive relationship with curriculum standards concerning the evolution of public English textbook content in Chinese HVE during the entire study period (approx. 1993 – 2023).

4.1 The Era of Foundation and Standardization Exploration (Guided by the 1993 Basic Requirements)

4.2 The Era of Quality-Oriented Education and Knowledge Update (Driven by the 2000 Basic Requirements)

4.3 The Era of Strengthening Vocational Competence (Guided by the 2012 Teaching Requirements)

4.4 The Era of Nurturing Function and Modernization Orientation (Under the Context of the 2021 Curriculum Standard)

4.5 Summary of Overall Evolutionary Path and Characteristics

Synthesizing the analysis of textbook content evolution across the four curriculum standard periods, a clear developmental trajectory emerges for public English textbooks in Chinese HVE over the past three decades. Closely following the adjustments in national vocational education policies and the deepening of developmental concepts, these textbooks have progressed from an initial stage emphasizing “Foundation + Preliminary Application” (1993 Basic Requirements era), through a phase focusing on “Quality-Oriented Education + Knowledge Update” (2000 Basic Requirements (Trial) era), transitioning to centering on the “Core of Vocational Competence” (2012 Teaching Requirements era), and ultimately moving towards a “Competence-Based Orientation with Multiple Integrations” (2021 Curriculum Standard era).

This evolutionary process exhibits the following main characteristics:

1. Prominently Policy-Driven: The promulgation of the four key curriculum standards served as the primary and most direct driving force behind the phased transformations in textbook content. Each revision of the standards reflected adjustments in the national positioning of HVE talent cultivation goals for the specific period, and these changes were rapidly transmitted to the guiding ideologies, content emphases, and format designs of textbook compilation.

2. Continuously Strengthening and Deepening Vocational Orientation: From initial attempts to incorporate vocational elements in the early stages, to the comprehensive highlighting of vocational competence in the middle phase, and further to the recent deep integration with the PCCC system, the vocational substance within textbooks has been continuously enriched and deepened, increasingly and closely serving students’ career development needs.

3. Shift of the “Nurturing Function” from Implicit to Explicit: Early textbooks primarily fulfilled the instrumental function of language tools, with the nurturing function remaining relatively implicit. With the introduction of the quality-oriented education concept and the emphasis on the fundamental task of “fostering virtue and nurturing talents” in the New Era, especially following the promulgation of the 2021 Curriculum Standard, the role of textbooks in value guidance and ideological nurturing has been elevated to an unprecedented level, requiring systematic and explicit integration.

4. Gradual Expansion of Contemporary Relevance and International Perspective: Textbook content moved from being relatively closed to more open, continuously incorporating new knowledge, new technologies, and new industry formats reflecting contemporary developments. Concurrently, attention to content related to international exchange and intercultural understanding has progressively increased.

5. Iterative Updating of Pedagogical Concepts and Methods: The design of tasks and activities within textbooks reflects a shift from teacher-centered, form-focused pedagogical concepts towards student-centered, use-focused approaches that emphasize task-driven learning and competence orientation. Digital transformation has become an irreversible trend in textbook development and resource provision.

Simultaneously, the evolutionary process also demonstrates certain aspects of continuity (such as the sustained attention to foundational language skills) alongside distinct stage-specific characteristics (with each standard period having clear content emphases). Variations were also observed in the degree and speed of textbook responses to standard requirements, revealing the complex interaction between policy transmission and practical implementation on the ground. Overall, guided by the curriculum standards, public English textbooks in Chinese HVE have undergone continuous adaptive adjustments and reformative innovations, and their evolutionary trajectory clearly maps the grand course of China’s HVE reform and development.

5.1 In-Depth Analysis of Driving Forces Behind Textbook Content Evolution

The evolution of textbook content is not an isolated phenomenon but the result of multiple interacting factors. Firstly, shifts in national macro-policies and educational philosophies serve as the fundamental driving force. From the early emphasis on serving economic construction and cultivating application-oriented talent, to advocating for quality-oriented education in the new century, and more recently highlighting the characteristics of VET as a distinct educational type, constructing a modern vocational education system, and emphasizing the task of fostering virtue and nurturing talents, each adjustment in top-level design has been transmitted, directly or indirectly, through the medium of curriculum standards to influence the value orientations, knowledge selection, and competence focus within the textbook. Secondly, socio-economic development and the demands of industrial upgrading act as significant external pull factors. As China’s economic structure transforms and technology advances, societal demands on the English proficiency of HVE graduates have shifted from basic reading, writing, and translation towards comprehensive communication skills for real-world work scenarios, particularly ESP competence in particular industries. This directly propelled the continuous deepening of vocational orientation in textbook content (especially after the 2012 Teaching Requirements). Thirdly, the development of foreign language education theories and practices provided internal impetus. From the traditional influence of the grammar-translation and audio-lingual methods, to the introduction and popularization of Communicative Language Teaching, TBLT, and ESP theory, and further to the deep integration of information technology with teaching and learning, these theoretical and practical advancements offered new ideas, methods, and presentation formats for textbook compilation, promoting the modernization of activity design, skills integration, and resource formats. These three forces have intertwined to jointly shape the evolutionary landscape of HVE English textbook content.

5.2 The Role and Limitations of Curriculum Standards in Textbook Content Evolution

This study clearly indicates that within the specific institutional context of Chinese HVE, curriculum standards have played a crucial role as the primary guide and strategic blueprint for textbook content reform. Their promulgation often rapidly triggered adjustments in the direction of textbook compilation, effectively guiding nationwide textbook development towards state-prescribed goals, reflecting the powerful influence of policy driving educational practice. Standards provide unified basic principles for textbooks, ensuring the fundamental quality and normativeness of teaching and learning.

However, the role of standards is not entirely infallible or unimpeded. On one hand, as textual stipulations, their interpretation and implementation may vary in practice. Factors such as compilers’ depth of understanding of the standard’s spirit, publishers’ market strategies, and selectors’ specific needs can lead to a certain time lag or discrepancy between textbook content and standard requirements. On the other hand, standards can sometimes be too macro-level or principle-based, making it difficult to fully cover the specific needs of all professional fields and regional developments, potentially limiting textbook distinctiveness and innovativeness. This complexity becomes particularly evident when considering the variations in textbook implementation at the local level. While a nationally planned textbook provides a common foundation, its actual application can differ significantly across regions and disciplines. For instance, a vocational college in a coastal, economically advanced city might have greater access to supplementary resources and industry partnerships, leading to deeper adaptation and extension of the textbook content. In contrast, an institution in a less developed region might prioritize the mastery of the core content provided. Similarly, the same public English textbook undergoes substantial “secondary development” in the hands of teachers from different disciplines. A nursing English teacher may integrate medical terminology and patient communication scenarios, while an engineering teacher might focus on technical manuals and project reports. These local-level adaptations, driven by regional context, disciplinary needs, and teacher capacity, highlight that the national textbook is not a fixed script but a foundational resource that is actively mediated and re-contextualized in practice, revealing the intricate interplay between national standards and local implementation.

Furthermore, a considerable period is often required from the promulgation of standards to the comprehensive development, promotion, and application of high-quality supporting textbooks, during which textbook construction might lag behind standard requirements. Therefore, while curriculum standards serve as important blueprints, the realization of their impact in practice is influenced by multiple mediating factors.

5.3 Achievements, Problems, and Challenges in China’s HVE English Textbook Development

Viewed through the lens of content evolution, Chinese HVE English textbooks have achieved significant accomplishments over the past three decades. First,vocational orientation has been markedly strengthened, with the relevance of textbook content to occupational demands substantially increased, effectively serving the cultivation of technical and skilled talent. Second, pedagogical concepts have kept pace with the times, gradually absorbing advanced international foreign language teaching theories, making task-based and communicative activity design mainstream. Third, the structural system has become increasingly refined, forming diversified textbook structures like “General English + Specialized Modules” or “Foundation + Modules”. Fourth, recent developments show a systematic focus on the nurturing function, reflecting requirements for holistic education.

Simultaneously, textbook content development faces ongoing problems and challenges. First, the depth and breadth of vocational content still need expansion; how to better adapt to rapid industry iteration and students’ diverse career development needs remains a major challenge. Second, balancing foundational general English skills with specific vocational English competence requires careful handling to avoid neglecting either aspect. Third, the methods for integrating the nurturing function need further exploration; achieving value guidance “like timely rain that silently nurtures” while ensuring language teaching effectiveness tests compilers’ wisdom. Fourth, although digital and intelligent transformation has begun, developing truly high-quality, integrated resources that promote deep learning remains a challenge. Fifth, issues persist regarding the match between textbook content and actual teaching contexts or teacher capacity.

5.4 Implications for Future Textbook Construction, Teaching Reform, and Teacher Development

The findings of this study offer multi-faceted implications for future development.

1. Textbook Construction: More agile and open mechanisms for textbook development and updating should be established. Deeper integration of industry and education, along with school-enterprise cooperation in compilation, should be encouraged, strengthening linkage with the PCCC system. Digital transformation should be continuously deepened, creating richer formats and more interactive intelligent learning resources. The integration of nurturing elements should emphasize both scientific rigor and artistry.

2. Teaching Reform: Teaching practices should synchronize with textbook development. Teachers need to actively explore pedagogical models that match the concepts in new textbooks (e.g., task-based, project-based, blended learning), making full use of digital resources to enhance teaching effectiveness.

3. Teacher Development: Training for HVE English teachers should be strengthened, particularly concerning the interpretation of new curriculum standard concepts, methods for using new textbooks, digital teaching capabilities, interdisciplinary knowledge (understanding relevant industry backgrounds), and competence in implementing curriculum ideological and political education, enhancing teachers’ ability to master textbook use and lead teaching reforms.

5.5 Potential Reference Value of the Chinese Experience for VET English Curriculum and Textbook Development in Other Countries

The rapid and systematic evolution of Chinese HVE English textbooks under the strong guidance of curriculum standards provides a valuable case study for other countries facing similar challenges. Specifically, the following experiences may offer points of reference. First, the effectiveness of unified national curriculum standards in promoting large-scale curriculum and textbook reform within a VET system. Second, the continuous exploration and practice of balancing general language proficiency with specific vocational needs (tracing the path from separation to integration). Third, the attempt and associated challenges of integrating national development strategies, cultural heritage, and values education into the vocational foreign language education system. Fourth, the experience and issues encountered in state-promoted digital transformation of textbooks. Naturally, the Chinese experience has its unique context, and other countries should fully consider their own national conditions, educational systems, and developmental stages when drawing comparisons. The Chinese case presented in this study helps enrich the comparative research landscape of international VET curriculum and textbook development. To place this in a more concrete global context, China’s state-led, top-down curriculum reform model presents a contrast to the more industry-led dual VET system found in many European countries, such as Germany, where apprenticeship and workplace needs often directly co-author the curriculum. While the Chinese approach ensures rapid and large-scale policy implementation, the German model fosters deep industry integration from the outset. In comparison to many Southeast Asian nations that are also in the process of rapidly developing their VET systems, China’s decades-long, systematic effort to balance general English proficiency with specific vocational needs – and more recently, to integrate national cultural identity into textbooks – offers a longitudinal case study of policy-driven evolution that can inform similar endeavors in the region. This brief comparison helps to highlight the unique characteristics and potential global relevance of the Chinese experience.

6.1 Main Research Findings

This study systematically examined the evolutionary trajectory of public English textbook content in China from 1993 to 2023, against the backdrop of four key HVE public English curriculum standard reforms. The findings reveal that Chinese HVE public English textbook content exhibits clear, phased evolutionary characteristics. Its overall path closely follows the reform directions of the curriculum standards, achieving a profound transformation from an emphasis on “basic language knowledge and preliminary application” (1993 standard era), to a focus on “quality-oriented education and knowledge update” (2000 standard era), then strengthening the “core of vocational competence” (2012 standard era), and finally moving towards emphasizing the “nurturing function and modernization development” (2021 standard era). Curriculum standards played a crucial role in top-level design and macro-control throughout this process, significantly shaping the guiding ideologies, content selection, skills emphasis, vocational representation, and task design of the textbooks. The vocational orientation of textbook content was continuously strengthened, pedagogical concepts were constantly updated, and recent developments show a systematic integration of nurturing elements and digital features, clearly mapping the historical imprint of China’s HVE reforms.

6.2 Limitations of the Study

This study has certain limitations. First, this study’s focus on nationally representative planning textbooks, while ensuring an analysis of the “intended curriculum”, has inherent limitations regarding generalizability. This approach does not fully capture the rich diversity of textbook adoption and adaptation across China’s vast regions and varied vocational disciplines (e.g., engineering, nursing, business). The actual “implemented curriculum” is inevitably shaped by local factors, including regional economic priorities, school-specific policies, and the unique linguistic demands of different professional fields. Therefore, the findings of this study represent a macro-level evolutionary trajectory, while the micro-level complexities of implementation at the local level present a valuable avenue for future research. Future studies employing a case-study methodology could investigate these variations, providing a more nuanced understanding of how national curriculum standards are interpreted and enacted in diverse contexts.

Second, this study primarily employed content analysis, focusing on the evolution of textual characteristics themselves. It did not deeply investigate the actual implementation of these textbooks in the classroom or their real impact on student learning outcomes, which would require empirical methods such as classroom observations or the analysis of teacher and student feedback.

Third, although efforts were made towards objectivity, the content analysis process might still be influenced by researcher subjectivity. Finally, concerning the latest 2021 Curriculum Standard, due to its recent promulgation, the analysis of its impact on textbook evolution relies more on trend judgment and observations of initial practices; its long-term effects require further longitudinal tracking.

6.3 Recommendations for Future Research

Based on the findings and limitations of this study, future research could be deepened in the following directions. First, conduct large-scale surveys on textbook usage and empirical studies on effectiveness to examine the application differences and learning outcomes of various textbooks in actual teaching. Second, conduct large-scale empirical studies from teachers’ and students’ perspectives, including surveys, interviews, and classroom observations, to understand their comprehension of, needs for, and feedback on textbook content, and to assess the actual teaching impact of these materials in diverse classroom contexts. Third, further explore new forms and models of HVE English textbooks in the context of digitalization and intelligent technologies, investigating their deep integration with teaching. Fourth, undertake broader international comparative studies, situating the development of Chinese HVE English textbooks within the larger context of global VET reforms. Fifth, continuously track the specific implementation of the 2021 Curriculum Standard in textbooks and its actual impact on the quality of talent cultivation.