Abstract: Based on the National Health and Family Planning Committee's 2014 National Population Dynamic Monitoring "Social Integration and Mental Health" survey data, the social integration of migrants was measured from four dimensions: economic integration, cultural adaptation, psychological integration and identity. The structural equation model was established to explore the internal structure of social integration, and the mediating effect was verified. The results show that: (1) the improvement of economic integration has a direct facilitating effect on the realization of cultural adaptation, psychological integration and identity of the floating population; (2) cultural adaptation and psychological integration affect the identity of the floating population, and meanwhile play a partial intermediary role in the impact of economic integration on identity. Therefore, we should continue to improve employment channels for the floating population, and create a fairer employment environment. Moreover, more attention should be paid to the social integration status of the floating population, so as to meet their multi-dimensional integration needs of culture and psychology. Besides, it is necessary for us to guide the local residents to establish a rational attitude and gradually eliminate their discrimination against the floating population.