Abstract: The hydraulic machinery running on the muddy river suffers from erosion by sediments, resulting in deformation and damage to the flow components of the hydraulic machinery, which seriously threatens the safe operation of the power plant. This study used a rotating jet facility to investigate the influence of sediment concentration on the impact abrasion and erosion characteristics of hydraulic machinery materials by the weight loss method and scanning electron microscopy. The results show that the cumulative weight loss of materials from impact abrasion and erosion almost increases linearly with the sediment concentration. When the sediment concentration is below 60kg/m3, the cumulative weight loss of the three materials increases slowly. When the sediment concentration exceeds 60kg/m3, the weight loss of the materials increases rapidly. As the concentration of sediment increases, impact erosion causes more serious damage to the materials, but the damage caused by cavitation shows a weakening trend. The higher the surface hardness of the material, the better its resistance to cavitation erosion, and the lower the critical sediment concentration at which the weight of abrasion and erosion is equal. The cavitation effect can affect the angle at which sand particles collide with the surface of the material, resulting in a greater horizontal impact load of particles. The abrasion marks show lip edges and material accumulation, and sand particle cutting damage dominates at higher sediment concentrations.