Abstract: In order to provide technical support for river regulation planning and propose drifting water supply scheme in the lower reaches of water conservancy projects, a two-dimensional full hydrodynamic model is adopted to simulate the different conditions with the river regulation or not. The downstream river channel of Sanhekou Water Control Project is taken as an example, where are the beautiful scenery on both sides of the river channel and few dangerous banks of submerged reefs. The elevation of the river bed is generally about 514~526 m, and the thickness of the sand and pebble layer of the river bed is 5~10 m, which provides a guarantee for the implementation of the rafting project. Based on the operation of the upstream water conservancy, hydraulic elements and related statistics on different cross sections were calculated under each working condition of drainage, which is beneficial to putting forward the drift river regulation and water supply scheme. The results show that the two-dimensional hydrodynamic model can successfully simulate the downstream river channel of a water conservancy project with high efficiency and high accuracy under different discharge conditions, and provide effective technical support for the planning of river water entertainment facilities. For saving water resources and reducing the amount of engineering construction, the dredging width of the river channel should be 6 m. Under this working condition, the upstream water conservancy project only needs to discharge 4 m³/s. The minimum water depth of the cross-sections is 0.50 m, the minimum water surface width is 4 m, and the minimum flow velocity is 1.02 m/s.