Introduction: Depression and anxiety are among the most important health priorities in today's world. The aim of this study was to investigate the relationship between emotion regulation with depression and anxiety: the mediating role of mindfulness.Methods: Design This study was descriptive and correlational study that of all male and female students of Semnan University in Mahdishar city, 350 people were selected by convenience sampling method. All participants were asked to complete Garnefsky cognitive emotion regulation questionnaire (CERQ) and five facet mindfulness Baer and colleagues (FFMQ) and Beck Depression and Anxiety Scales.Results: To analyze the data using Pearson correlation, structural equations were used using AMOS software. The results of structural equations showed that a significant direct path from emotional regulation on depression and anxiety, which was reported as 0.53 and 0.63% respectively. Also There is significant indirect pathway from emotional regulation on depression and anxiety through mindfulness with path coefficient 14.0 percent.Conclusion: It can be concluded that emotion regulation is associated with depression and anxiety symptoms in the university students while mindfulness skills mediate this relationship. Therefore, the mindfulness training and emotion regulation skills training is recommended for the development and promotion of student Psychological health.