The analytical expression of radial electromagnetic force wave of surface-mounted PMSM was deduced by analytical method and the amplitude, order, frequency of radial electromagnetic force wave were gained based on above analytical expression. The influences of radial airgap flux density harmonic on the radial electromagnetic force wave were analyzed, it proposed that the 3pthorder airgap flux density harmonic could be used to reduce the doublefrequency radial electromagnetic force wave, resulting in lower noise and vibration. The finite element simulated model was established to prove the above method and the correctness of the method was validated.