The existing literature on environmental efficiency focuses on economic and social factors, and rarely on the role of local leadership. Thus, this study aims to measure the environmental efficiency and analyze the impact of mayors' characteristics on environmental efficiency. By using the metafrontier-stochastic frontier analysis two-step estimate method, the average value of the overall environmental efficiency in China is only 0.523, which is high in the eastern region and low in the central and western regions. Empirical results show that mayors' tenure plays an inverted U-shaped effect on environmental efficiency. Mayors who are highly educated, young, and aware of environmental protection can improve environmental efficiency. Moreover, mayors' experience in official exchange can improve environmental efficiency; mayors with work experience in the central government are effective in terms of environmental governance. The policy implication is that improving the educational level of leaders, appointing young cadres, and strengthening official exchanges can effectively improve environmental efficiency.