Objective To explore the psychological factors influencing non-suicidal self-injury （NSSI） in depressive disorder adolescents. Methods From May 2022 to November 2023， 127 adolescents with depressive disorder admitted to the Department of Psychology of the 904th Hospital （Changzhou Branch） of the Joint Logistics Support Force of the Chinese People's Liberation Army were selected as participants. Patients were divided into non-NSSI group （n=59） and NSSI group （n=68） based on the occurrence of NSSI. Childhood Trauma Questionnaire-Short Form （CTQ-SF）， Self-Esteem Scale （SES）， Trait Coping Style Questionnaire （TCSQ）， Adolescent Resilience Scale， and Defense Style Questionnaire （DSQ） were used to assess psychological factors such as childhood abuse， self-esteem， coping styles， psychological resilience， and defense mechanisms in patients. Multivariate Logistic regression was used to analyze the influencing factors of NSSI in adolescents with depressive disorder. Results Univariate analysis showed that there were statistically significant differences in emotional abuse， physical abuse， emotional neglect， physical neglect， negative coping， total SES， emotional control， family support， total psychological resilience， and mature defense mechanism psychological trait scores between the two groups of patients （t=-6.741，-2.204，-3.991，-2.861，-5.665，3.826，2.223，4.580， 4.058， 4.501； all P＜ 0.05）. Multivariate Logistic regression analysis showed that emotional abuse ［OR=1.273， 95%CI （1.080， 1.501）， P=0.004］ and negative coping ［OR=1.129， 95%CI （1.032， 1.236）， P=0.008］ were risk factors for the occurrence of NSSI in adolescents with depressive disorder， while family support ［OR=0.825， 95%CI （0.691，0.984），P=0.033］ and mature defense mechanisms ［OR=0.918，95%CI （0.866，0.972）， P=0.003］ were protective factors for NSSI in adolescents with depressive disorder. Conclusions The incidence of NSSI is relatively high in adolescents with depressive disorder， and family support and mature defense mechanisms are protective factors for this behavior， while emotional abuse and negative coping are risk factors.