Abstract: In the perspective of "overflow of the migrant workers", this paper discusses the significance of Deng Xiaoping's South China Speech for the economic reform of China through the description of the relationship changes between the urban and the rural areas in China before and after the policy of reform and opening up. This paper points out that the migrant workers are not only the social phenomenon of the dual society as well as the heritage of the former economical system, but also the powerful element of the economic reform of China. As China's economic reform has been deepening after Deng Xiaoping's South China Speech, the " overflow of the migrant workers" has a growing influence upon the social and economic development. Facing the "historic challenge of Lewis Turning Point", China needs to deepen the reform to promote the development of the labor market in order to promote the sustained economic growth.