An active power factor correction circuit. The circuit comprises a voltage source having a first end and a second end, an inductor having an end coupled to the first end of the voltage source, a first rectifying device having an anode coupled to the other end of the inductor and a cathode, a second rectifying device having a cathode coupled to the cathode of the first rectifying device and an anode, a first switching device having a first terminal coupled to the anode of the first rectifying device and a second terminal, a second switching device, having a first terminal coupled to an anode of the second rectifying device and the second end of the voltage source and a second terminal, a capacitor having two ends coupled to the cathode of the second rectifying device and the second terminal of the second switching device respectively, and an auxiliary circuit for switching the first and second switching devices under zero voltage.