Objective: To explore the relationship between college students with financial difficulties, campus environment and mental health, and to explore whether physical activity can be used as a mediating variable to make campus environment affect mental health through it, so as to improve the mental health of college students. Methods: A total of 150 college students from five universities in Shanghai were selected by stratified random sampling. The basic information of the questionnaire was surveyed, the 3D accelerometer and GPS measured the intensity, time and trajectory of physical activity, the built environment factors were extracted by GIS, and the structural equation model was tested by AMOS 22.0. Results: Campus environment had a significant direct effect on the mental health of college students with financial difficulties, and the path coefficient was 0., respectively43, the order of its contribution is landscape elements, spatial configuration, building density, distance from sports venues, and the obvious direct and indirect effects on the mental health of college students with financial difficulties through physical activities, and the path coefficients are 032. 0.101;Campus environment and physical activities have a positive impact on the mental health of college students with financial difficulties. Conclusion: Campus environment and physical activities have direct and indirect effects on the mental health of college students with financial difficulties. By revealing the impact path of college students with financial difficulties' mental health, it is of great practical significance for the construction of urban communities, the improvement of campus environment, the promotion of physical activities, and the improvement of mental health in the new era.