The present invention discloses a high power factor phase-cut dimming power supply system, which includes an alternating current power supply, a phase cutting dimmer, a high power factor phase-cut dimming power supply, an LED lamp, or an LED light. The high power factor phase-cut dimming power supply includes an anti-interference circuit that corresponds to and adaptively connect with each other, an active power factor correction circuit, a power conversion circuit, a dimmer current maintaining circuit, a signal conversion circuit, a photoelectric coupler, a PWM signal amplifying circuit and a field effect transistor. The present invention provides a high power factor phase-cut dimming power supply. It has advantages of a high power factor, a load power without any limitation, a high efficiency, an output power as high as several hundred watts. It can be widely used in the field of high power factor phase-cut dimming power supply.