The motion law of castor capsule during shelling process is of great significance to the study of shelling damage. Based on the theory of bonding contact, a simulation model of castor shelling process was established to simulate the movement of castor capsule in the shelling drum. The results showed that in the process of castor shell peeling simulation, when the speed reached 8.50m/s, the capsule of castor just broke after collision with Q235 steel, and the inner seed was not damaged. Therefore, the speed at 8.50m/s was set as the target value. When the rotation speed was 250r/min, the shelling gap was 7mm, and the filling rate was 40%. In the single factor analysis, the influence of drum revolution on the maximum pressure and velocity of particles were significant. With the increase of revolution, the maximum pressure between particles was decreased from 68.78N to 68.10N. The maximum velocity of particles was increased from 8.92m/s to 12.99m/s, and the shelling rate was increased from 91.23% to 91.28%, and then it was decreased to 88.89%. The influence of shelling clearance on the maximum pressure and velocity of particles was followed: with the increase of shelling clearance, the maximum pressure between particles was decreased from 76.93N to 58.69N, the maximum velocity of particles was increased from 12.14m/s to 12.99m/s, and then decreased to 10.05m/s. Furthermore, the shelling rate was firstly decreased from 92.50% to 89.59%, and then increased to 91.41%. In the process of shelling, the average velocity of particles in Xaxis direction was decreased from 4.17m/s to 3.m/s to 7.59m/s;and the average velocity of particles in Zaxis direction was decreased from 6.58m/s to 6.24m/s. In the stage of initial shelling, the particles were concentrated in the middle of the shelling drum, and some castor seeds were accumulated. The castor capsules bounced up after touching the inner drum, fell down and rotated with the inner drum, and then moved toward the outlet. During the stable shelling stage, the castor was concentrated and evenly distributed near the outlet of the shelling drum, and rotated with the inner drum. At the end of the shelling stage, the particles were concentrated at the bottom of the shelling drum, and then moved to the bottom continuously. Most of the castor was discharged from the right side of the shelling chamber. Through simulation, the optimal parameter combination of the shelling process was obtained as follows: rotation speed was 350r/min, shelling clearance was 5mm, and the filling rate was 40%. The test results were as follows: rotation speed was 350r/min, shelling clearance was 5mm, and the filling rate was 30%. Since among the three factors, the rotation speed and shelling clearance were extremely significant factors, and the filling rate was significant factor, the difference was within a reasonable range. The study provided theoretical support for the design of castor shelling machine and its related components. 