Abstract: The process of new urbanization not only promotes rapid socio-economic development, but also leads to increasingly severe water environment problems. This study took 11 provinces (municipalities directly under the central government) in the Yangtze River Economic Belt (YREB) as the research objects, and adopted entropy method and coupling coordination degree model to measure the coupling coordination degree of new urbanization and water environment. Spatial autocorrelation model and grey correlation degree model were used to explore the spatio-temporal evolution and the driving factors. The results showed that: (1) From 2009 to 2020, the comprehensive level index of water environment in the YREB remained stable, and the overall development trend of new urbanization and the coupling coordination of new urbanization and water environment was good. From the perspective of spatial evolution, the coupling coordination degree showed a pattern of "downstream>midstream>upstream". The regional differences slowed down, and the overall growth rate was relatively slow. (2) The coupling coordination of new urbanization and water environment had a significant positive spatial autocorrelation, and the local spatial autocorrelation exhibited clustering convergence characteristic, with a strong spatial correlation. (3) The factors that affected the coupling coordination of new urbanization and water environment in descending order of intensity were: industrial structure, population aggregation, technological innovation, economic drive, and government capacity. The degree of influence of each factor on the coupling coordination degree had significant regional differences. Therefore, it is necessary to pay full attentions to the regional resource advantages of the upper, middle and lower reaches of the Yangtze River, to promote the coordinated development of new urbanization and water environment.