<p>High-power permanent magnet electric drive gear transmission system is commonly used in low-speed and heavy-load environment. However, prolonged operation under variable speed and load conditions can lead to gear wear and resonance. To investigate the electromechanical coupling dynamic characteristics influenced by the coupling effects of gear wear and resonance, a feedforward control method for permanent magnet synchronous motor (PMSM) is introduced. A electromechanical coupling dynamic model is established, incorporating the coupling characteristics of both gear and bearing. The variation law of gear meshing stiffness and backlash under the influence of tooth surface wear are simulated and analyzed. The results indicate that gear wear has a greater influence on the tooth root than on the tooth tip, on the high-speed gear than on the low-speed gear, and on the 2nd order resonance of the gear system than on the 1st order resonance. The influence of gear wear on the resonance response is primarily observed at the resonance frequency 3<i>f</i>_<i>m</i>34 and the meshing frequencies <i>f</i>_<i>m</i>12 and 2<i>f</i>_<i>m</i>12. Additionally, both gear wear and resonance have a greater impact on the PMSM load torque. Gear wear exerts a greater influence on the <i>q</i>-axis current than on the phase current.</p>