From the perspective of time and space,the effect of regional water use intensity was decomposed into the industrialization effect,industrial structure upgrading effect,water-saving technology effect of the tertiary industry,carrying capacity effect of domes-tic water use,and the scale effect of urban population water use.The LMDI decomposition expansion model of temporal and spatial dif-ferences in regional water use intensity was constructed.Taking the Yangtze River Economic Belt as an example,the driving channels and internal influencing mechanisms of industrial structure upgrading on temporal and spatial differences in water use intensity were explored in depth.The results showed that the upgrading of industrial structure was an important factor to inhibit the increase of water use intensity in the Yangtze River Economic Belt from 2000 to 2020,but its inhibitory effect had weakened year by year since 2012,and had turned to promote the growth of water use intensity,and then turned to inhibitory effect in 2020.Since 2011,there had been a weakening trend in the driving force of inhibiting or promoting the increase of water use intensity compared with Shanghai.The industri-al structure adjustment of provinces and cities under the trend of service could inhibit the increase of water use intensity compared with Shanghai.Anhui Province,Jiangxi Province,Hunan Province,Jiangsu Province and Sichuan Province should strengthen the rational allocation of water resources between industries(especially between the first and second industries)and optimize the water consump-tion structure within the industry(especially the second industry).Guizhou Province,Hunan Province,Yunnan Province and Hubei Province had a low level of service,and still needed to further develop the tertiary industry.

China's economy is in an important transition period of rapid development and high-quality development. The contradiction between water resources allocation and regional economic development needs has become a major strategic problem faced by the national economy and the people's livelihood. In this paper, the industrial structure effect that affects the change of regional water use intensity is decomposed into industrialization effect, industrial structure upgrading effect, tertiary industry water-saving technology effect, and domestic water extraction effect from the spatial dimension. The LMDI decomposition expansion model of regional water use intensity is constructed. Taking the Yangtze River Economic Belt as an example, the influence mechanism of industrial structure upgrading on the spatial dimension difference of water use intensity is deeply explored. The study shows that since 2016, the improvement of the level of industrial structure upgrading in each province and city can inhibit its increase in water consumption intensity compared with that in Shanghai. Jiangxi, Hunan, Yunnan, and Sichuan need to optimize the allocation of water resources among industries, especially between the primary and secondary industries. Anhui, Jiangxi, Chongqing, Yunnan, and Sichuan need to improve the service level of the tertiary industry.