Abstract: In order to assess ecological environmental performance of 11 provinces (municipalities) in Yangtze River Economic Belt (YREB) reasonably, the environmental performance research was carried out by constructing environmental performance index (EPI) system. Considering the influence of economic development levels on regional environmental protection input capacity, the differential index evaluation values under different economic development levels were proposed using the Environmental Kuznets Curves (EKC) and the mean value theory, and EPI of 11 provinces (municipalities) which reflected the degree of regional efforts to environmental protection were calculated by using entropy method. The results showed that from 2011 to 2017, the environmental performance of YREB as a whole showed an upward trend and the annual average EPI of 11 provinces (municipalities) in YREB was increased from 49.74 to 61.70, but the solid waste control performance declined. In 2017, the EPI score of 11 provinces (municipalities) ranking from high to low was Hunan (68.76), Anhui (66.62), Chongqing (64.86), Sichuan (64.30), Zhejiang (61.26), Shanghai (60.96), Jiangxi (59.53), Hubei (58.80), Guizhou (58.68), Yunnan (57.65) and Jiangsu (57.24), and the average EPI of downstream reaches, middle reaches and upstream reaches was 59.82, 63.43 and 61.37,respectively, indicating that spatial distribution of environmental performance was relatively balanced. According to the clustering of EPI and GDP per capita, the 11 provinces (municipalities) were divided into three groups, i.e. accelerated transformation area, steady development area and slow upgrading area, to fit in different development schemes. The evaluation method reflected the efforts of each region to protect the ecological environment to a certain extent, by taking the differences of economic development level in different regions into account, which could provide effective supplement of conventional environmental performance research.