The present invention relates to a low loss boost circuit used in power conversion equipment of power supplies or other power systems. It comprises controlling a duty cycle of a power switch; realizing voltage boosting and regulating of the output voltage through the energy storage in a boost inductor; reducing the reverse recovery current using an auxiliary inductor, wherein a secondary winding of the inductor supplies additional energy thereto and provides a path for transferring the energy from the auxiliary inductor to the energy storage capacitor. The present invention has high efficiency and is suitable for power converter with PFC, such as, telecommunication power supply and uninterrupted power supply.