Sports behavior is an important means and behavior mode for health promotion. Promoting youth sports behavior and improving their health level from a positive and healthy perspective are related to the grand strategy of building a healthy China. Based on the COM-B theory，using Delphi，questionnaires，confirmatory factors，structural equation modeling and other methods，the index system is established from four dimensions including sports behavior，sports ability，sports motivation and sports participation opportunities，and the influence and interaction between different dimensions have been explored as well. The results show that fitness ability，opportunity acquisition，sports motivation，and social support conditions all have a significant positive impact on youth sports behavior； Fitness ability has the highest degree of explanation for potential variables of sports behavior and is the most critical factor； sports motivation is the mediating variable. The development of youth sports behaviors should pay attention to the synergistic effect of ability cultivation，opportunity giving and motivational incentives，emphasize the cultivation of active well-being concepts for individuals，strengthen sports learning and promote sports ability improvement，and transfer control rights and strengthen social coordination support etc.