Motor vibration was an important performance indicators and motor vibration analysis could improve its structure and provide a theoretical basis for performance optimization. In order to understand the vibration characteristics of the motor, the first six order natural frequencies and corresponding vibration modes of the motor rotor vibration system were obtained, with the modal analysis of the rotor of the permanent magnet synchronous motor carried on by the Ansys finite element analysis software. The accuracy of the Ansys finite element analysis was verified by the hammering method of modal experiment. The result of analysis showed that the motor dod not appear resonance phenomenon, so the design of the motor rotor was reasonable. This research content has certain guiding significance for the design and optimization of permanent magnet synchronous motor.