Aiming at the problem of misalignment caused by the gear axis deflection changing the meshing state, a gear meshing misalignment diagnosis method based on the motor stator current signal is proposed. Using the electromagnetic torque of the motor dynamic mathematical model as an intermediate variable, combined with the bending-torsional-axis dynamics model of the gear system, an electromechanical coupling dynamics model of the traction motor-gear transmission system was established. The influence of different axis errors on the stator current signal of the electromechanical coupling dynamics model was explored. The stator current spectrum under different conditions was obtained through spectrum analysis, and the current spectrum characteristics corresponding to the gear axis error were clarified. The research results show that the motor stator current spectrum under axis error shows sidebands related to the power supply fundamental frequency and the gear pair meshing frequency; the impact of the meshing plane angle error on the current spectrum frequency is more obvious than the center distance error and the vertical meshing plane angle error, which is the reason for the non-standard gear intrusive engagement status monitoring provides a reference.