Base on the environmental pollution problems caused by urbanization, this paper analyzes the social formation mechanism of the environmental pollution in the process of the current "spontaneous" (bottom-up) urbanization, considering that the self-interest of the participants of urbanization, the increase in consumption and the local government's excessive pursuit of economic growth as the main causes of the pollution problem occurred during the urbanization. On this basis, this paper proposes the conception of institutional guarantee on ecological environment for the new-type urbanization, focusing on "planning constraint", "people oriented" and "law enforcement first".