In order to know the character of twist vibration for vertical rolling mill processing,the model of twist vibration was established. The model parameter computation and the simulation of rolling process were carried out by MATLAB. The bifurcation diagram, the phase diagrams and the poincare diagrams were obtained. The simulation results show that the vibration rule of instability, quasi\|periodicity,  periodicity were found in the course of the angular frequency from low to high. The resonance vibration occurs when the system is in the low frequency and the rolling process is instable, a rational rolling process rule shall be designed to avoid resonance vibration in practice.