Abstract: Based on the permanent magnet synchronous motor dynamic model (Park model), considering the influence of current injection on the electromagnetic torque of permanent magnet synchronous motor, the electromagnetic torque model of PMSM and the torsional vibration model were built for the permanent magnet synchronous motor and the mechanical rotor to solve the torsional vibration response of the external excitations. The influence of injected harmonic currents on torsional vibration was analyzed, and the active vibration condition was obtained. And finally, it was verified by a test rig. The test results show that when the harmonic current is satisfied with the active vibration condition, the torsional vibration can be reduced by the injected harmonic current.