Abstract: As the main body of migrant workers, most of the new generation of migrant workers are in the golden stage for marriage and childbearing. Their fertility desire has important practical significance for the urbanization and population sustainable development in China. Through vertical and horizontal comparisons, it found the fertility desire of the new generation of migrant workers significantly decreased, with an obvious modernized characteristic, reaching new generation inter-city migrant population. The differences of gender, marital status and educational level in their fertility desire weakened significantly. Based on the theory of urban adaptation, this paper analyzed the influencing factors of their fertility desire, and found that the influence of economic adaptation, social adaptation, psychological adjustment and institutional adjustment is significantly enhanced. The improvement of economic adaptation, social adaptation and psychological adaptation will significantly reduce their expected number of children in the new generation of migrant workers. This makes the development of urbanization and the phenomenon of reducing the fertility of the new generation of migrant workers coexist. There are two contradictions between urbanization and population sustainable development. However, institutional adaptation can significantly improve their fertility desire, which provides a possibility and path for the coordinated development of urbanization and population sustainable development.