Abstract: Biting and slippage may incur the vibration of the main drive system of rolling mill, which is the major cause of most system damage. A 3-degree scattering dynamic model considering the clearance was developed according to the main driving system of a heavy plate mill. By using Runge-Kutta method, the mathematical model of the dynamic response of periodic power was calculated. The Poincaré section was chose as the closure interface. According to the chaotic dynamics and the engineering analysis, it was proved that this model is capable of simulating chaotic motion. This study provides reference for the research on the vibration control of this kind of rolling mill’s driving system.