This study aims to examine the linguistic features, emotional self-disclosure, and thematic patterns of the online self-disclosure discourse of individuals with depression in China. First, the study findings indicate several key linguistic characteristics in the online self-disclosure discourse of individuals with depression in China. Specifically, regarding the use of personal pronouns, the highest frequency is observed for the singular first-person pronoun “I”, which demonstrates the self-focused narrative mode prevalent in Chinese online depression discourse. Notably, the use of third-person pronouns constructs a state of isolation in terms of both external identity and internal emotions, further highlighting the confrontational nature of the discourse. Besides, in terms of lexical usage features, the online self-disclosure discourse of individuals with depression in China can be categorized into three main types: (i) frequent use of disease-related vocabulary, (ii) frequent use of negative terms such as “no” or “not”, and (iii) frequent use of emotional words. Second, regarding emotional self-disclosure, the use of negative emotional words significantly outweighs the use of positive ones, resulting in an overall dominance of negative sentiment. Additionally, the emotional orientation of the semantic content should be interpreted in the specific contextual meaning. Third, as for topic characteristics, the online self-disclosure on social media reveals five key topics: emotional representation, emotional challenges, life status, pathological manifestations, and emotional needs. In light of these findings, this study aims to enrich the research on emotional health discourse to some extent and provide a comprehensive perspective to enhance social understanding of individuals with depression, with the hope of contributing to the improvement of overall mental health in society.