Abstract: Accurately measuring the green efficiency of water resources in cities along the Yangtze River Economic Belt is of great significance to the rational utilization of water resources and green development and construction of cities along the Yangtze River Economic Belt. The SE-SBM model (Super-Efficiency Slacks-Based Model) is used to measure the green efficiency of water resources in 45 cities along the Yangtze River Economic Belt from 2010 to 2019. Combined with the decomposition of Theil index, the root causes of regional differences in green efficiency of water resources are explored, and the ML index method (Malmquist-Luenberger) is used to explore the internal causes of changes in green efficiency of water resources; Furthermore, the difference between the actual value and the optimal value of water resources input and water pollutant output is used to calculate the water-saving and emission reduction potential of 45 cities along the Yangtze River Economic Belt. The results show that: First, during the study period, 77.8% of the 45 cities along the Yangtze River Economic Belt were inefficient in the green efficiency of urban water resources, and the spatial distribution of green efficiency of water resources shows that the lower reaches of the Yangtze River Economic Belt > the upper reaches > the middle reaches; Second, from 2010 to 2019, the green efficiency of water resources in 45 cities along the Yangtze River Economic Belt was on the rise, but the green efficiency of water resources in 9 cities along the Yangtze River Economic Belt, including Zhaotong, Lijiang, Panzhihua, Guiyang, Tongling, Huzhou, Shaoxing, Zhoushan and Ezhou, was on the decline, which was affected by the changes of pure technical efficiency, scale efficiency and technological progress to varying degrees; Third, the water-saving potential, sewage emission reduction potential and industrial wastewater emission reduction potential are divided into three sections of “low, medium and high”, and 45 cities along the line are divided into five types of “three high, two high, one high, medium and three low”, of which Yueyang, Ma’anshan, Huangshi and Jingzhou belong to the “three high” type; In terms of spatial pattern, cities with “three low” types of water-saving and emission reduction potential show the agglomeration trend of “large settlement, small scattered”. Based on the above research results, this study can provide countermeasures for promoting the rational development and utilization of urban water resources along the Yangtze River Economic Belt and realizing regional high-quality green development.