To simulate the continuous engagement of gear pair under resonance state

the contact finite element method was described and proved to be reasonable by comparing the meshing stiffness with national standard. The research object was a helical involute gear pair

the natural frequency of torsional vibration was got by spectral analysis method and frequency response analysis method. The occurrence

development and steady state of gear pairs torsional resonance were simulated numerically

and several dynamic parameters were analyzed quantitatively. The results showed that

the separation during the meshing process made the effect of meshing impact more significant. The maximum vonMises stress increased by 20% compared with the value when the meshing frequency was 3000Hz.