Returned migrant workers can not start a business without the new-style urbanization and the new-style urbanization relies on the driving force of local economic and social development that returned migrant workers bring to. Business start-up of returned migrant workers is an important force of mass entrepreneurship and innovation. The key of the new-style urbanization is to reach a harmonious development between urban and rural areas and rural population can be settled with a job in urban areas. This paper discusses the role of business start-up of returned migrant workers in promoting rural population settlement in urban areas and harmonious development between urban and rural areas；the factors，conditions and characters of business start-up of returned migrant workers；the state and local government policies of supporting returned migrant workers to start up a business and good practices and experiences；and the challenges that returned migrant workers is facing in business start-up and the recommendations.