After 10 sessions, all the participants including the non-responders and the responders (ie, decrease in Yale-Brown Obsessive Compulsive Scale [YBOCS] scores ≥ 25%) will enter the maintenance phase for 6 months. The participants in MBCT group will continue MBCT treatments at home. The participants in drug therapy group will continue on their treatment program without changing the type and dosage of medication they have been using. By comparing clinical symptoms, such as obsessive and compulsive symptoms, anxiety, depression, quality of life and other clinical symptoms and behavior, the study will describe the short-term and long-term effects of MBCT in patients with DSM-IV obsessive-compulsive disorder (OCD).