Abstract: Based on the characteristics of the daily regulation wave of hydropower stations, the water surface lines in the rising and falling stages are calculated by using an one-dimensional steady flow model and an unsteady flow sediment model. The water surface lines in the reach from Yichang to Shashi, downstream of the Three Gorges, before and after completion of the Three Gorges Reservoir are calculated by using a steady flow sediment model. Considering the joint operation of the Three Gorges and Gezhouba Hydropower Stations, influences of the daily regulation planning of the hydropower stations on the water surface slope of the downstream reach of the Three Gorges Reservoir are studied.