BACKGROUND: The discrepancies of the ideal self and the actual self (called as type A in this article), the objective self and the actual self(called as type B), the looking glass-self and the actual self(called as type C) are important study subjects and closely related to health psychology.OBJECTIVE: To probe into relationships between the discrepancies of type A, B, C self-concepts and mental health about Chinese college students, and try to provide scientific basis for mental health education of college students.DESIGN: Sampling investigation and cross-sectional study design based on the college student SETTING: Department of Psychology of Capital Normal University. PARTICIPANTS: From January to March 2002, in Beijing, we randomly chose 337 undergraduates who were of grade 2-3 from 9 classes in China University of Political Science and Law University(97 students), Universityof Petroleum, Beijing(85 students), China Public Security University(103students) and Capital Normal University(52 students). In Shanghai, Shanghai University(150 students from 7 classes in grade 2): In Changchun, Northeast Normal University(120 students from 4 classes in grade 1 -2).The total of participants were 607, but 51 participants were excluded for all kinds of reasons, at last, 556 valid participants took part in this study.METHODS: The self-concept-scale questionnaires was used for this study,including four subscales of the ideal self, the actual self, the object self and the looking-glass-self which were used to measure Chinese undergraduates'self-concept-discrepancies of A, B and C types; symptom checklist-90 scale (called SCL-90) was used to measure undergraduates' mental health. MAIN OUTCOME MEASURES: The self-concept-discrepancies of three types(A, B, C), mental health and their relationships of Chinese college students. RESULTS: ① The descriptive statistics about the discrepancies of self-concepts of three types(A, B, C) of college students: type A (65.0±39.2)discrepancy was bigger than type B(-30.1± 28.2); type B was bigger than type C (-0.11± 24.7); ② Compared to the adult normal of symptom checklist-90(SCL-90), the college students responded to SCL-90 was normai, showing majority of college students were mental healthy; ③ Type A and B discrepancies of college students significantly correlated with 10 factors of SCL-90(P＜0.01), whereas the correlation between type C discrepancy and 10 factors of SCL-90 was not significant; ④ Regression analyses predicting SCL-90 showed that A type(β=0.32) discrepancy contributing to SCL-90 was more bigger than type B (β= 0.24), type B was more bigger than type C (β= -0.14).CONCLUSION: The correlation of the discrepancies of the ideal self and the actual self, the discrepancies of the objective self and the actual self withmental health were statistically significant; but the correlationof the discrepancy of the looking-glass-self and the actual self with mental health was not statistically significant.