Spoil dump is an important problem in soil and water conservation schemes for hydropower cascadedevelopment.Improper setting of spoil dumps can easily narrow the river channel and influence river flooddischarge.Aiming at this question,a new calculating method based on numerical simulation of river flow wasproposed.Using the hydrodynamics module in MIKE 21model,changes of water level and flow field wereobtained by two-dimensional simulation before and after the existence of spoil dumps.This method solvedthe hydraulic calculation problem in soil and water conservation schemes,especially in areas lacking hydrological data and engineering experience.It also provided technological evidence for soil and water conservation engineering measure design on spoil dumps.