Abstract: In the context of tightening constraints on water resources, the panel data from 2005 to 2014 of 26 cities in the Yangtze River Delta Urban Agglomeration is adopted, and SBM model is used to measure the industrial water use efficiency in this region. Then, the spatial differences of the industrial water use efficiency in the Yangtze River Delta Urban Agglomeration are analyzed by the decomposable Theil index. The results show that the industrial water use efficiency level of the Yangtze River Delta Urban Agglomeration is low: the 10years average industrial water use efficiency is 0591 8 when the undesirable outputs are not considered, and it is 0519 7 when the undesirable outputs are added. The within group difference of industrial water use efficiency is the main source of the total difference and it has the trend of increasing with time. The contribution rate of Zhejiang Province to the within group difference is the largest, followed by Anhui Province, and Jiangsu Province has the lowest contribution rate. Although the differences of industrial water use efficiency between the cities in Jiangsu Province is not very big, the overall level is still low, Shanghai’s industrial water use efficiency is a little higher and on a steady rise. Therefore, narrowing the within group differences is an important way to realize the overall increase of industrial water efficiency in the Yangtze River Delta Urban Agglomeration