During the grinding train operation process, the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency. The coupling vibration among the frame, the grinding wheels and the wheelsets will seriously affect the stability of the grinding force. In this paper, the coupled mechanical model of the grinding wheel/rail is established based on the contact mechanics theory, which is embedded as a submodel into the dynamic model of the multi-rigid buggy. The interaction among the frame, the grinding wheels, and the wheelsets are analyzed by setting the convex irregularity on the rail. The grinding effect is evaluated in combination with the subway’s long wave corrugation grinding conditions. The results show that when the grinding buggy passes the convex irregularity, the vibration excited by the wheelset system has a significant impact on the dynamic behavior of the grinding wheels. The vibration of the grinding wheel is mainly transmitted between the grinding wheel and the frame, less affecting the wheelset. For the long wave corrugation of the subway, the grinding effect of the grinding wheel has a certain correlation with the phase angle of the wheelset through the corrugation. The research results provide an important reference for the setting of the grinding pattern.