Abstract: To explore the relationship between college students' obsessive-compulsive symptoms, cognitive flexibility, and the mediating role of emotion regulation (cognitive reappraisal and expression inhibition) in between the two, the Obsessive-compulsive Inventory-Revised, Emotion Regulation Questionnaire, and the Chinese version of the Cognitive Flexibility Inventory were used to measure 687 college students. The results showed that: (1) College students' Obsessive-compulsive symptoms were negatively correlated with cognitive flexibility and cognitive reappraisal, and positively correlated with expression inhibition. Cognitive flexibility was negatively correlated with expression inhibition, and positively correlated with cognitive reappraisal; (2) Cognitive reappraisal and expression inhibition played a partial mediating role between the total score of compulsion and cognitive flexibility, with the relative mediating effects accounting for 23.51% and 10.07%, respectively. Conclusion: Obsessive-compulsive symptoms of college students not only can directly affect cognitive flexibility, but also play a role through the indirect effects of emotion regulation strategies.