Abstract: Aim at limitation of the traditional single-phase simulation method in the process of simulation of vertical spiral mixing mill（vertical mill）, such as less visual reflection characteristics, and the low simulation accuracy caused by the failure to consider the effect of fluid on the medium, etc. A CFD-DEM coupling simulation method is used to simulate the grinding process of vertical mill wet grinding, which can effectively improve the accuracy of wet grinding simulation. Firstly, three-dimensional model of vertical mill and the fluid and medium ball model completing parameter calibration is set, the motion of medium ball in the grinding cylinder under wet grinding condition is visually simulated and analyzed. Combined with laboratory test, this paper takes the spindle torque as the evaluation index of simulation accuracy, defines a regional medium ball motion speed algorithm, describes the motion law of the medium ball in the grinding cylinder, and finally analyzes the normal and tangential force of the medium in the grinding process. The results show that average relative error between the axial torque value simulated by the coupled simulation method and the test torque value is 6.98%. The maximum and minimum average velocities of the medium are 0.164 6 m/s and 0.011 2 m/s respectively, and the positions where the velocity gradient is larger are located around the spiral mixing shaft, it is more conducive to the grinding of minerals. The normal force is 5 times of the tangential force when the medium contacts. Thus, the coupled simulation method can effectively improve the simulation accuracy. The abrasive materials are mainly subject to the extrusion and crushing of the medium.