Although many studies have confirmed the close association between chronotype and depression, the prediction between chronotype and depression, as well as the mechanisms of their influence are rarely investigated in adolescents. This study aimed to confirm the bidirectional prediction between chronotype and depression, and to exam the mediating effects of cognitive reappraisal, expressive suppression, and rumination on the association between chronotype and depression in adolescents. This was a longitudinal study over a 5-month period with 2 surveys (N = 634; 41.32% male, 58.68% female). Pearson correlation analysis was utilized to examine the relationship among all variables. Hierarchical regression analysis was conducted utilized to analyze the relationship between chronotype and depression. Conduct mediation analysis to exam the mediating roles of cognitive reappraisal, expressive suppression, and rumination on the association between chronotype and depression. Results showed that after controlling for gender, age (T1), age (T2), and depression (T1), chronotype at baseline negatively predicted depression 5 months later. After controlling for gender, age (T1), age (T2), and chronotype (T1), depression at baseline negatively predicted chronotype 5 months later. Chronotype indirectly predicted depression though cognitive reappraisal, expressive suppression, and rumination, but depression indirectly predicted chronotype though cognitive reappraisal, and rumination. This study found a bidirectional prediction between chronotype and depression, andthe underlying mechanism of the chronotype predicting depression and the underlying mechanism of depression predicting chronotype were different.