In the process of new urbanization, it is important to focus on promoting the construction of urban social service system while eliminating all kinds of rigid institutional obstacles. By means of the innovation of social service mechanism, it is possible to meet the demands of agricultural transfer population to achieve humancentered urbanization. Taicang city of Jiangsu province introduces the “three social linkage” mechanism to serve agricultural transfer population. Taicang explores a new social service model in the community which uses social community, social organization and social workers to promote the service and improve social integration. Taicang adopts action strategies of giving the institutional priority, focusing on the key projects, valuing the professional orientation of service to achieve the new breakthrough in promoting urbanization quality of agricultural transfer population. However, there are still some problems, such as the single source of fund, the weak power of social organization and community and the limitation of service content and coverage. Such problems should be solved in an innovative way.