Objective: This study investigates the impact of physical activity on negative emotions among university students and examines the mediating influence of self-efficacy, aiming to furnish empirical insights and a theoretical framework to enhance and optimize the mental health of this population comprehensively. Methods: Using the cluster random sampling method, 5341 university students were selected from three universities. The questionnaire included demographic information about university students, physical exercise behaviors, expressions of negative emotions such as depression and anxiety, and self-efficacy in physical exercise. The types of questionnaires included the Physical Activity Rating Scale (PARS-3), the General Self-Efficacy Scale (GSES), and the Depression Anxiety Stress Scales (DASS). Results: 76.877 % of university students had low exercise. The detection rates of depression, anxiety and stress in negative mood were 77.041 %, 64.276 % and 47.931 %, respectively. There were significant differences in physical exercise and negative mood scores among university students of different genders and grades. University student. Negative emotions were significantly correlated with physical exercise and self-efficacy (P