The formation of the dual structure of inner city on the one hand is the extension of urban and rural dual structure in the new era，and on the other hand is the formation of low-income class on the process of corporate restructure and urban transformation. There is a huge gap between urban residents and urban low-income groups in the economic conditions and status，social security，public service and so on. It brings about some problems like social stratification，increased urban poverty and intergenerationalization，aggravating social conflicts，difficulty of urban management，and it affects the advance of new urbanization. Reasons for its formation includes a big gap between the rich and poor，land finance，institutional factors，public service and social security and other aspects. Therefore，to break the dual structure of inner city，we must begin to take such measures as to build reasonable housing system，to protect the rights of farmers’ land income，to establish a diversified cost-sharing mechanism of migrant workers to become citizens，to speed up the construction of basic public service associated with the reform of household registration，and to lower the urban threshold to achieve a high-quality and sustainable new urbanization.