Moist particle electrolyte electrochemical mechanical polishing (MPE-ECMP) is an emerging technology that has difficulties in obtaining high-surface quality workpieces. In order to solve this problem, the contact characteristics of the workpiece and electrolyte particles were investigated, and the discrete element simulation software Altair EDEM was used to explore the influence of workpiece inclination angle and speed on the number of contacts and contact force. The results show that when the inclination angle is 30°, the contact number between electrolyte particles and the workpiece per unit time is the largest, and the tangential force is the largest, which is 3.38 mN. The tangential force is the smallest at 90°, 1.21 mN. As the rotational speed of the workpiece increases, the number of electrolyte particles in contact with the workpiece per unit of time becomes less, and the normal and tangential forces of electrolyte particles in contact with the workpiece tend to increase. When the polishing potential (vs. Hg/Hg2SO4) is 0.8 V and the workpiece is tilted at 30° for 1 h, the surface roughness is reduced from Sa433.51 nm to Sa22.43 nm, and the surface roughness is reduced by 94.8%. The results demonstrate that the adjustment of workpiece tilt angle and rotational speed can effectively improve the polishing accuracy of MPE-ECMP, the reduction of surface roughness is jointly determined by the number of contacts and contact force, and EDEM can effectively simulate the flow characteristics of electrolyte particle motion, which lays the foundation for further research of MPE-ECMP.