Since reform and opening up, China is experiencing the largest population migration in the world. With the development of the market economic system and the widening of economic disparities between regions, the surplus labor force in the central and western regions gradually migrates to the eastern developed regions to obtain more employment opportunities and higher wages. In the context of large-scale cross-regional migration, population has a complex preference for the choice of migration direction. When the level of economic development is comparable, the labor force in choosing the place to move, to a large extent, depends on their understanding of the local social situation and the local interpersonal network. Social capital can reduce uncertainty and transaction costs, improve communication efficiency, help collective actions, and reduce principal-agent problems. Therefore, to explain the mechanism of population inter-provincial migration on social capital will help us to have a deeper understanding of the preferences and laws of population inter-provincial migration.　　Combining with previous literature, this paper first discusses the mechanism of social capital affecting inter-provincial migration. The study finds that the difference in individual level will significantly affect the level of social capital. By influencing residents’ trust in the system, their perception of social risks and the effectiveness of their own social network and social capital can transfer employment information, save the cost of migration, and promote the integration of migrants in residential places. If they can benefit from social capital, migrants may be able to make cross-provincial migration decisions.　　On the basis of the mechanism analysis, this paper uses " degree” and " influence” from three census data to show the dynamic process of inter-provincial migration with a migration rate of more than 5%, and combines with related variables in China Family Panel Studies （CFPS） micro-panel data to show the social capital level. These works find that areas with higher levels of social capital attract a large number of people to move in, while areas with lower levels of social capital become the center of population migration. In order to test this phenomenon, this paper uses CFPS panel data to establish a Logit model to carry out empirical research on the relationship between social capital and inter-provincial migration of population. Empirical research shows that the level of social capital has an important impact on inter provincial migration. Residents are more likely to make cross-provincial migration decisions because of the gap between the rich and the poor, household registration reasons, unfair treatment in government affairs, and high degree of trust with others. In terms of the mechanism, the older the individual is, the better the marital status is, and the higher the industrial structure attribute of the occupation is, the lower the social capital level in the level of institutional trust is, the less likely it is to occur inter-provincial migration behavior; the older the individual is, the higher the educational level is, and the higher the industrial structure attribute of the occupation is, the lower the social capital level in the level of generally trust is, the lower the probability of occurrence of inter provincial migrationis. The conclusion of this study has positive significance for the government to formulate relevant policies on talent introduction and social management.