Objectives To investigate the mediating effect of working memory on social function in patients with depressive disorder. Methods This study is a cross-sectional study. A total of 149 depressive disorder patients who met the DSM-IV diagnostic criteria were included in Beijing Anding Hospital from June 2017 to Augest 2018. The Patient Health Questionnaire （PHQ-9）， Sheehan Disability Scale （SDS）， and Self-ordered Pointing Task （SOPT） were applied to evaluate patients' depression severity and social function. Hierarchical regression model was used to test the mediating effect of working memory between depression severity and social function. Results （1） The PHQ-9 total score was positively correlated with the SDS total score （r=0.41，P ＜ 0.01）， with the click numbers of SOPT （r=0.19，P ＜ 0.05）， and the SDS total score was positively correlated with the click numbers of SOPT （r=0.16，P ＜ 0.05）. （2） The results of hierarchical regression model and bootstrap showed that the total number of SOPT clicks had partial mediating effect on the total score of PHQ-9 and SDS， and the proportion of mediating effect was 4.09%. Conclusions The social function of patients with depressive disorder is indeed affected by the mediating effect of working memory， but it is only a partial mediating effect.