Objective: To explore the role of emotion regulation in the process of depression affectingcollege students’ suicidal ideation. Methods: 583 college students were investigated with the ShortDepression-Happiness Scale (SDHS), Positive and Negative Suicide Ideation (PANSI) and EmotionRegulation Scale (ERS). Results: (1) The results of correlation analysis showed that depression wasnegatively correlated with reappraisal and positively correlated with suppression and suicidal ideation;reappraisal was negatively correlated with suicidal ideation, and suppression was positively correlatedwith suicidal ideation; (2) The mediation model test results showed that depression can positivelypredict suicidal ideation. Specifically, depression can affect suicidal ideation by reducing reappraisaland increasing suppression. Conclusion: Positive emotion regulation is helpful to reduce the harm ofdepression to college students’ suicidal ideation.