Abstract: In view of problem of electric harmonic pollution produced by diode rectifier and phase-controlled rectifier, a three-phase unity power factor PWM rectifier was designed. The topology of power circuit, control strategy of PWM rectifier and design methods of hardware circuit and software were introduced in details. The experiment result showed that the PWM rectifier adopts control strategy of direct current of double loop-closed of voltage and current, which has high power factor and low total harmonic distortion in AC-side, and reduces pollution to power network.