With rapid development of popular science voluntary service, promoting college students' capacity has become a research issue. Based on the capacity building theory and the questionnaires of 139 college student volunteers of science popularization, the article firstly processed the data using Factor Analysis Method, and then took empirical analysis on the influencial factors of college student volunteers' capacity promotion in science popularization using Multiple Regression Model. The results show that college management, capacity awareness, social environment, process management have significant effects on college student volunteers' capacity promotion in science popularization. In order to promote college student volunteers' capacity, capacity awareness should be cultivated as the foundation, institution capacity building, including college management and process management should be strengthened as the platform, and social environmental capacity-building should be enhanced as a guarantee.