The protective role of students' perceptions of school climate against mental health problems has been supported in previous research, yet relatively little is known about the mechanism underlying school climate's influence on Chinese youths' depressive symptoms. Guided by the process--person-context-time model, this study examined the mediating effect of psychological "suzhi" (a Chinese cultural construct comprising a hierarchical, integrated set of positive psychological qualities) on the longitudinal association between perceived school climate and depressive symptoms among Chinese adolescents. Students (N = 1,151; 52.2% boys; mean [M]age = 16.24, standard deviation [SD] = 0.70) from one Chinese high school participated in a 3-wave (each wave was 6 months apart) longitudinal study. Multilevel mediation models were used to analyze between- and within-person effects on the longitudinal association between perceived school climate and depressive symptoms. The results indicated that students who perceived a more positive school climate reported lower depressive symptoms than students who perceived a more negative school climate (between-person effect); however, students who perceived their school climate positively did not always directly report lower depressive symptoms across time (within-person effect). Psychological "suzhi" mediated the association between perceived school climate and depressive symptoms at both the between- and within-person levels. Students who perceived a more positive school climate had increased psychological "suzhi," which, in turn, decreased their depressive symptoms. The findings provided implications for school-based mental health prevention services by highlighting the need for promoting both positive school climate and students' psychological "suzhi."