Abstract: With the Stochastic Frontier Production Function, based on the data of 279 prefecture-level or above cities in China from 2003 to 2010, bringing the environmental pollution into the urbanization efficiency evaluation system as an input factor, this paper measures the technical efficiency of urbanization process under the environmental constraints from four aspects, including demographical, economical, spatial and social; and analyzes the impact of population density, industrial structure, government policy, regional scale and some other factors on urbanization efficiency. The main results are as follows: (1) In comparison, during the investigating time, the efficiency of economic, spatial and social urbanization are higher, while the demographical one is lower. In terms of spatial distribution, the urbanization efficiency value of each type is highest in east and lowest in west. (2) Population density, industrial structure and government policy all have positive impact on demographical and social urbanization efficiency, while regional scale has positive impact on demographical urbanization efficiency but no significant impact on social one; regional scale has negative impact on economical urbanization efficiency; population density has negative impact on spatial urbanization efficiency, while both industrial structure and regional scale have positive impact. Finally, this paper suggests that the overall efficiency of regional urbanization should be improved by coordinating various influencing factors.

Key words: environmental constraints, the efficiency of urbanization, influencing factors, stochastic frontier, Stochastic Frontier Production Function