Objective To explore the abnormal social decision-making behavior of adolescent depression patients， so as to reflect the problem of its social function. Methods From September 2020 to February 2021， a total of 49 adolescent patients who were treated in outpatient or inpatient department of Beijing Anding Hospital and 25 healthy adolescents in community were selected as research subjects. Hamilton Depression Scale-17 （HAMD-17）， the Patient Health Questionnaire-9 （PHQ-9） and Generalized Anxiety Disorder （GAD-7） were applied to assess patients' depression and anxiety symptoms. The repeated measurement ANOVA was used to compare the difference in the acceptance rate and reaction time of the ultimatum game paradigm scheme between the two groups of subjects， and the post task questionnaire was used to assess the cognitive difference between the two groups of subjects on the fairness of the scheme after the task was completed. Results The HAMD-17， PHQ-9， and GAD-7 scores of patients in the depression group were higher than those in the healthy control group， with statistically significant differences （P＜ 0.05）. There was no statistically significant difference in acceptance rates between the two groups of subjects （P＞ 0.05）. In terms of acceptance rate， the main effect of fairness is statistically significant （F=201.760， P＜ 0.01， partial η2 =0.737）， and there is an interaction between fairness and proposer categories （F=8.791， P ＜ 0.01， partial η2 =0.109）. There was no statistically significant difference in reaction time between the two groups of subjects （P ＞ 0.05）. In terms of reaction time， the main effect of scheme fairness is statistically significant （F=42.755， P ＜ 0.01， partial η2 =0.373）， and the main effect of the scheme proposer is statistically significant （F=5.333， P ＜ 0.05， partial η2 =0.069）. There is an interaction between fairness and proposers （F=8.946， P＜ 0.01， partial η2 =0.111）. There is no statistically significant difference in the total score of the post task questionnaire between the two groups of subjects （P＞ 0.05）. However， the score of question 1 in the post-task questionnaire of the depression group was 6.4 （1.0， 10.0） points， which was lower than the 8.0 （2.0， 10.0） points of the healthy control group， with a statistically significant difference （Z=-3.235， P＜ 0.01）. Conclusions There is no significant abnormality in the social decision-making behavior of adolescent depression patients， which is related to their understanding of fairness in allocation plans.