Objective: To explore the characteristics and relationship between physical activity and self-efficacy of college students during the COVID-19 epidemic, so as to provide evidence for the orderly development of physical education and curriculum reform of college students after their return to school. Methods: A total of 6 227 college students were collected from 8 districts of China by using convenient sampling method and snowball sampling method, and the physical activity and self-efficacy of all participants were assessed used by the International Physical Activity Questionnaire Short Form (IPAQ-S) and the General Self-Efficacy Scale(GSES). Results: In the terms of general self-efficacy, the score of male students was significantly higher than that of female students, the score of freshman was significantly higher than that of other grades(t/F=7.32, 5.56, P<0.01). In terms of physical activity, the middle and high level physical activity of girls was significantly higher than that of boys, but the proportion of boys meeting the recommended amount was higher(P<0.01). Low level physical activity was the highest in junior college students(31.75%), medium level physical activity was the highest in freshmen (46.75%) and sophomore student (48.13%), and high level physical activity was the highest senior college students (30.40%). The moderate level of physical activity was the highest in all BMI groups, while the lean group had the lowest level of low level physical activity (15.70%) and the highest level of high level physical activity(37.31%), and the lowest proportion meeting the recommended amount(P<0.05). Self-efficacy had a positive predictive effect on physical activity(OR=1.04, 95%CI=1.03-1.05). Conclusion During the COVID-19 epidemic, there are significant differences in general self-efficacy and physical activity among college students by gender, grade and BMI. The general self-efficacy has a positive impact on physical activity, suggesting that college physical education should pay attention to students- self-efficacy, while considering individual and group differences, and promote physical activity level through self-efficacy improvement.