Objective: To explore the mental health of postgraduate students and its influencing factors, and promote the development of the mental health of postgraduates in China. Methods: We used cluster sampling on 9 522 postgraduate freshmen, all data of SCL-90 was analyzed by SPSS21.0. Results: The total mental health of postgraduates was not bad (the positive rate was 1.0%~8.4%), and obsessive-compulsive disorder, interpersonal sensitivity as well as anxiety were the top three mental illness. The factor scores of female, rural, non-only-child, post-90s and only-child of post-90s postgraduate freshmen were higher than those of male, urban, only-child, post-80s and only-child of post-80s postgraduate freshmen. Many differences between them were showed significant or extremely significant difference (P < 0.01 or 0.001). Conclusion: The mental health of postgraduate freshmen still had many obstacles. Therefore, corresponding measures should be taken to reinforce it.