This paper selects energy consumption data of 11 provinces in YRB and 19 provinces and cities in non-YRB from 2014 to 2016 and constructs a shared border Metafrontier non-radial directional short model, adding CO2 and AQI indicators as undesirable factors, in order to evaluate the total efficiency and the input and output efficiencies of these two regions. The results are as follows. (1) From the changes in the score and ranking of the two regions' total environmental efficiency, only two provinces in YRB show a slight decrease, while most of them show a stable or rising trend; seven provinces in non-YRB have a low rising rate. This means during the study period that YRB made more progress at energy conservation, emission reduction, and pollution control than other provinces and cities in non-YRB. (2) The efficiency scores of energy consumption, GDP, CO2, and AQI emissions are different in each province. Overall, the situation of YRB is better than that of non-YRB. Not only is the efficiency score of each index higher, but the efficiency difference between provinces and cities within the region is small, which is conducive to the linkage effect of the region and the realization of green coordinated development.
Keywords: Environment efficiency; Metafrontier; Metafrontier directional distance; Yangtze River Economic Belt.