The invention discloses a motion control device of a trimming machine. The motion control device of the trimming machine comprises a machine frame and a machine plate. A distribution box is arranged on the inner wall of the machine frame. The outer wall of the top of the machine plate is fixedly provided with an Y-axis motor and an X-axis motor through bolts. The four sides, close to the Y-axis motor and the X-axis motor, of the outer wall of the top of the machine plate is provided with linear guide rails. An output end of the X-axis motor is connected with a lead screw. The outer wall of thetop of the machine plate is provided with a lead screw seat. The central axis of the lead screw is provided with a fixing block. The output end of the Y-axis motor is connected with a second lead screw. The outer wall of the top of the machine plate is provided with a second lead screw sat. A second fixing block is arranged on the central axis of the second lead screw. According to the motion control device of the trimming machine, an abrasive wheel and a grinding wheel walk in cooperation with the linear guide rails and are driven by numerical control, the abrasive wheel and the grinding wheel walk stably on the guide rail faces, and therefore trimming is stable and reliable; through X-axis and Y-axis motion, in cooperation with front-back movement and adjustment, the overall change of the trimming device can be executed by numerical control, and therefore the automation degree is high.