Based on Lagrangian tracking of solid particles' motion trajectories in a solid-fluid flow field, by applying Finnie ductile materials erosion model, Reynolds stress model and discrete phase model to the continuous phase and dispersed phase, the solid-liquid erosion and motion trajectory of solid particle and the impact progress between solid particle and machine surface were simulated successfully. The volume content of solid phase in two-phase flow was lower than 10% in this simulation model. According to the simulation result, the related parameters of solid particle, such as density and diameter, and rotational speed of impeller greatly influenced the motion trajectory and the impaction with machine surface of solid particle. The solid particle with large mass was apt to move toward to the working surface and impacted the inlet head of impeller. By contraries, little particle was liable to impact the rear-end surface of impeller near to the outlet side. The large solid particle could repeatedly impact machine surface easier than the little particle. The numerical simulation result was verified by a comparison experimental analysis result.