Objective · To explore the relationship among depressive symptoms, attributional style and obsessive-compulsive symptoms in patients with obsessive-compulsive disorder. Methods · Seventy patients with obsessive-compulsive disorder who met the diagnostic criteria of Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (DSM- Ⅳ) were selected. The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) was used to evaluate the severity of obsessive-compulsive symptoms, the Beck Depression Inventor- Ⅱ (BDI- Ⅱ) was used to measure the depressive symptoms, and the Attributional Style Questionnaire (ASQ) was used to measure the attributional style. The correlations among obsessive-compulsive symptoms, depressive symptoms and attributional style as well as the mediating role of obsessive-compulsive symptoms between attributional style and depressive symptoms were analyzed. Results · The globality dimension of negative events in attributional style was positively correlated with obsessive-compulsive symptoms and depressive symptoms (both P<0.05), and obsessive-compulsive symptoms were also positively correlated with depressive symptoms (P=0.000). The mediating effect analysis showed that the mediating role of obsessive-compulsive symptoms between the globality dimension of negative events and depressive symptoms was 0.105 (95%CI 0.031-0.218), with an mediating effect ratio of 44.20%. Conclusion · Obsessive-compulsive symptoms in patients with obsessive-compulsive disorder may play a completely mediating effect between the globality dimension of negative events in attribution style and depressive symptoms.