Background: Regular physical activity is an effective means to enhance university students' subjective well-being. However, current research needs to understand how physical activity enhances the subjective well-being of Chinese university students. Therefore, the study investigated the mechanism of physical activity's impact on university students' subjective well-being and the mediating roles of cognitive reappraisal and resilience in this mechanism. Methods: The physical activity scale, subjective well-being scale, cognitive reappraisal scale and resilience scale were used to investigate 1350 university students, and the relationship between physical activity, cognitive reappraisal, resilience and university students' subjective well-being was verified through correlation analysis, regression analysis and a Bootstrap method. Results: (1) There is a significant positive correlation between physical activity, cognitive reappraisal, resilience and university students' subjective well-being (p < 0.01); (2) physical activity, cognitive reappraisal and resilience all have a significant positive effects on university students' subjective well-being (p < 0.01); (3) cognitive reappraisal and resilience have significant mediating roles in the process of physical activity affecting university students' well-being, with mediating-effect values of 0.052 and 0.285; (4) the chain-mediating role of cognitive reappraisal and resilience in the process of physical activity affecting university students' well-being is significant, with the chain-mediating effect value of 0.062. Conclusion: Promoting university students' participation in physical activity not only directly enhances university students' subjective well-being but also indirectly improves university students' subjective well-being through cognitive reappraisal and resilience. [ABSTRACT FROM AUTHOR]