Abstract: During the long-term operation of Mupo hydropower station, the sediment deposition in the riverbed has been seriously affecting the safe operation of the power station. In order to reveal the distribution characteristics of sediment in the river channel and put forward its improvement measures, this study combines numerical simulation and experimental validation, and uses the DPM model to analyze the solid-liquid two phases of the river channel model of Mupo hydropower station on the basis of the high degree of consistency between the experimental and simulation data, as well as the modified design for the sand barriers in the tailwater channel where the sediment distribution is obvious, so as to compare and analyze the distribution of the liquid phase, the particle distribution, and the distribution of the particles at the tailwater channel. The results indicate that: the liquid-phase volume fraction and particle mass concentration distribution area in the river channel increase with the growth of flow, but the liquid-phase volume fraction area increases and the particle mass concentration distribution area decreases after the modification; the particle distribution in the tailwater channel is positively correlated with the flow, and the sediment distribution in the area of the tailwater channel sand barriers after the modification is effectively controlled, which also verified the success of the modification of the sand barriers. The results of this study can provide effective engineering value for the stable operation of the unit and normal drainage of the tailwater channel.