The electromagnetic vibration level is one of the important evaluation indicators of permanent magnet synchronous motor (PMSM). In order to effectively suppress the electromagnetic vibration of PMSM, the analytical analysis model of the radial electromagnetic force generated by the interaction of rotor permanent magnet magnetomotive force, stator winding current magnetomotive force and stator slot was established in this paper. Then the field-circuit coupling analysis model of the variable parameter vector control system of PMSM was established. Taking an 11 kW interior PMSM as a prototype, the acoustic frequency spectrum of the electromagnetic vibration noise generated by the main low-order electromagnetic force during the stable operation of the motor was obtained using the mechanical impedance method, and the frequency of the low-order electromagnetic force that plays a major role in the electromagnetic vibration of the motor was determined. At last, the genetic-ant colony algorithm was used to study weakening methods of the low order electromagnetic force with the above frequency by optimizing the stator slot parameters of the motor, so as to effectively suppress the electromagnetic vibration of the motor. The results show that the stator slot parameters determined by the method in this paper can effectively suppress the electromagnetic vibration of the motor, and have little impact on the operating performance of the motor.