One of the most important tasks of urbanization in China today is to accelerate large amount of migrants integrating into urban society．Different from existing researches which focus on hukou system and institutional reforms，this paper emphasizes the role of social capital and social mechanism in improving social integration of migrants，calling for a closer relationship between migrants and urban local residents．Improving the quantity and quality of Localized Social Capital ( LSC) would be a crucial factor contributing to social integration of migrants．The paper defines and measures LSC in three dimensions: Social Participation ( SP) ，Social Trust ( SC) and Social Intercourse ( SI) ，and analyzes how those LSCs have influenced social integration of migrants．While SP and ST have significant effect on migrants’social integration，the effect of SI is not significant．The paper discusses policy implications for enhancing migrants’LSCs to promote their social integration: encouraging more social participation and involvement in public affairs; cultivating mutual trust between migrants and local residents; and developing more positive intercourse and communications between migrants and local residents．