Abstract: This paper applies the DEA ratio model to calculate the environmental efficiency of Chinese provinces from 2005 to 2012. The results show: the pollutants significantly reduce the average efficiency of each region, so the efficiency evaluation without considering pollutants is not scientific; the environmental efficiency of the western region is the highest, followed by the eastern region and the middle region is the lowest. At the same time, this paper uses the multiple regression model to analyze the factors which affect the environmental efficiency, and finds that the AGDP, external trade and population density have a significantly positive effect on environmental efficiency; In contrast, the proportion of the second industry and the number of patents have a significantly negative impact on the improvement of environment efficiency; Investments in industrial pollution control don't have an obvious influence on environmental efficiency. Finally, some advices have been given based on the empirical research.