Objective: To explore the efficacy of sertraline plus clozapine in the treatment of obsessive - compulsive disorder (OCD). Methods: A total of 55 patients with OCD who met the criteria of CCMD -3 were randomly treated rapeutic group(n = 30) and control group( n = 25 ) for the treatment of 8 weeks. The efficacy was measured with Yale - Brown obsessive - compulsive scale( Y-BOCS), Hamilton depression scale (HAMD) and Hamilton anxiety scale(HAMA). Results: After treatment there were significant differences between two groups in overall response showed by the reduction rate of Y - BOCS, HAMD and HAMA total scores. Conclusions: Sertraline plus clozapine have a superior effectiveness in the treatment of OCD.