China's regional environmental efficiency evaluation: a dynamic analysis with biennial Malmquist productivity index based on common weights

China's economy in the past 10 years has developed rapidly and achieved great success, but at the same time, environmental problems have been deteriorating, seriously hindering the country's regional sustainable development. This paper proposes a common-weights DEA model based on "the priority of choosing common weights" to assess the environmental performance of 30 provinces from 2006 to 2015 and analyzes regional development in combination with China's economic division. This paper also introduces the biennial Malmquist Productivity Index (BMPI) to study environmental productivity levels during the 11th and 12th Five Year Plans (FYP) from a time series perspective. The results present a large gap in regional environmental efficiency, mainly manifested by the fact that the eastern and northeastern regions' environmental condition is obviously better than that of the central and western regions. BMPI analysis indicates that the overall environmental performances during the 11th and 12th FYPs did not improve significantly, with a clear imbalance in the western region, implying that its development potential is huge. On this basis, we offer some suggestions for improving the environmental performance of different regions.