Abstract: Taking cascade hydropower development in the middle and lower reaches of the Hanjiang River as an example, the influences of cascade development on the water environment were discussed from four aspects, i.e. the form of water flow, runoff, water quality and water temperature, by collecting water environment data before and after the cascade hydropower development. The results show that the development of the middle and lower reaches of the Hanjiang River has significantly changed the form of water flow where the project located, which is mainly reflected in decreasing the average flow rate of the reservoir area while increasing the average water depth. As the control hub of the middle and lower reaches of the Hanjiang River, the scheduling of Danjiangkou hub reservoir has obviously adjusted the average water runoff of the downstream reaches monthly. Cascade hydropower development has not deteriorated the water quality of Wangfuzhou and Cuijiaying sections. Danjiangkou cascade has significantly affected the water temperature of downstream, while Wangfuzhou and Cuijiaying cascade has no significant effect on the water temperature of downstream reaches.