In the radial vibration suppression of the motor, the current harmonic injection method is an effective method. The radial force model of surface permanent magnet synchronous machine (SPMSM) is analyzed, and the relationship of the frequency, amplitude and phase between harmonic current and radial vibration harmonic is obtained. A current harmonic injection method is derived by using the current closed-loop transfer function in vector control, which can adjust the frequency, amplitude and phase of current harmonics to realize the change in the amplitude of radial vibration harmonics. one current harmonic is selected to suppress one even-order radial vibration harmonic, and the gradient descent method is adopted to online calculate the frequency amplitude and phase of the current harmonics injected at the minimum amplitude of radial vibration harmonics. In order to avoid the influence of the single current harmonic on the high radial vibration harmonics, a sequential vibration suppression method is proposed to realize the comprehensive suppression of every low-even-order vibration harmonics. Finally, an on-line control system for the radial vibration suppression of SPMSM with multi-current harmonics injection is designed. The prototype is a 750W SPMSM, the amplitude of all low-even radial vibration harmonics are suppressed significantly by this method, which verifies the correctness and effectiveness of this method.