Based on the operating principle of PWM (pulse-width modulation) rectifier, aiming at the major factors which influence the power factor of rectifier, switching frequency and its losses, an improved traditional method of SVPWM (space-vector pulse-width modulation) has been proposed by applying the SVPWM technology. And three-phase voltage vectors are synthesized to a rotary space one, the voltage of AC side of the rectifier can be controlled. Based on the coordinate transformation from three phase to two phase of AC source voltage, phase angle of source voltage vector can be determined, the power factor of rectifier can be controlled, the harmonic contamination and pollution of power network can be reduced effectively.