Objective To preliminarily verify the effectiveness of dialectical behavior therapy （DBT） combined with lithium carbonate in adolescents with non-suicidal self-injury （NSSI）. Methods From June 1 to December 31， 2023， 60 adolescents with NSSI visiting Qinhuangdao Jiulongshan Hospital were selected as subjects. The subjects were divided into DBT group and DBT+ lithium carbonate group by 1∶1 using randomized numerical table method， 30 cases in each group. DBT group was treated with single DBT， and DBT + lithium carbonate group was given lithium carbonate in addition to DBT. At baseline， three months after treatment， and six months after treatment， the Adolescent Non-suicidal Self-injury Assessment Questionnaire （ANSAQ）， Non-suicidal Self-injury Function Questionnaire， Hamilton Depression Rating Scale-24 （HAMD-24）， and Young Mania Rating Scale （YMRS） were used to evaluate the NSSI behavior and functional status， as well as the severity of depression and mania symptoms in both groups of subjects. The general information and observation indicators between the two groups were compared using t-test， Mann-Whitney U test， and chi square test. Simple effects analysis was conducted using repeated measures analysis of variance for those with significant interaction between groups and follow-up time or significant main effects between groups/ follow-up time. Results Before treatment， there was no statistically significant difference in the total scores and dimension scores of ANSAQ and Non-suicidal Self-injury Function Questionnaire between the two groups of patients （P ＞ 0.05）. At the third and sixth months after treatment， the total scores of ANSAQ and Non-suicidal Self-injury Function Questionnaire and the scores of each dimension of the patients in DBT + lithium carbonate group were lower than those of DBT group， and the differences were all statistically significant （P＜ 0.05）. Repeated-measures analysis of variance showed that the total and dimension scores of ANSAQ as well as Non-suicidal Self-injury Function Questionnaire were statistically significant for different treatment time main effects， group main effects， and time and subgroup interaction effects （all P ＜ 0.05）. Simple effect analyses showed that DBT + lithium carbonate group had lower total scores on the ANSAQ and Non-Suicidal Self-Injury Function Questionnaire and scores on all dimensions than DBT group after three months of treatment and after six months of treatment， and the differences were statistically significant （all P＜ 0.05）. The incidence of NSSI in patients in DBT + lithium carbonate group was lower than that in DBT group at the third and sixth months after treatment， and the differences were statistically significant （P ＜ 0.05）. The differences in HAMD-24， HAMA and YMRS scores at baseline between the two groups were not statistically significant （P ＞ 0.05）. Repeated-measures analysis of variance showed statistically significant HAMD-24， HAMA and YMRS scores across treatment time main effects， group main effects， and time and subgroup interaction effects （all P＜ 0.05）. Simple effect analysis showed that HAMD-24， HAMA and YMRS scores were lower in DBT + lithium carbonate group than in DBT group after three months of treatment and after six months of treatment， and the differences were statistically significant （all P＜ 0.05）. Conclusions Combined lithium carbonate on the basis of DBT has significant efficacy advantages over single DBT， which can effectively reduce the incidence of adolescent NSSI and significantly improve the anxiety， depression and mania symptoms in adolescents with NSSI.