ABSTRACT This study aimed to investigate the associations of childhood trauma and its facets with depressive symptoms in depressed adolescents during the post COVID-19 epidemic, and explore the potential mediating role of social peer rejection in these associations. A total of 413 adolescents with depressive disorders completed the Chinese version of the Child Trauma Questionnaire Short Form, the Social Peer Rejection, and the Children’s Depression Inventory. Childhood trauma (β = 0.42, p < 0.01) and social peer rejection (β = 0.18, p < 0.01) were positively related to depressive symptoms, after adjustment for demographic factors. Furthermore, social peer rejection partly mediated the relationship between childhood trauma and depressive symptoms, and the mediation effect ratio was 17.0% (p < 0.001). This study found that childhood trauma and social peer rejection are both risk factors for depressive symptoms, and social peer rejection played a mediating role in the relationship between childhood trauma and depressive symptoms.