<p>The industrial robot joint drive system is prone to electromechanical coupling resonance phenomenon under electromagnetic excitation and load disturbance, which affects the robot end positioning and tracking accuracy. Therefore, considering the vibration characteristics and electromechanical coupling effect of the motor rotor, the electromechanical coupling torsional vibration model of the rotor system under electromagnetic excitation and end-load impact is established. The multi-scale method is used to solve the approximate solution of the electromechanical coupling model in the case of principal parameter resonance, and the steady-state solution and stability of the motor rotor system are determined by numerical method. The effects of torsional stiffness, end-load disturbance and permanent magnet remanence on torsional vibration characteristics of rotor system are studied. The results show that reasonable control and design of electromagnetic and mechanical parameters of permanent magnet synchronous motor (PMSM) can avoid the instability phenomena such as jumping and bifurcating in the industrial robot joint drive system under the influence of electromagnetic excitation and load disturbance. At the same time, considering electromagnetic excitation and load disturbance, deep mechanical and electrical coupling torsional vibration research has important theoretical and practical significance for the fault diagnosis and suppression of the industrial robot joint drive system under complex working conditions and the design of high-performance systems.</p>