A simple zero current switch circuit includes a first coil set and a second coil set that are wound at a selected coil ratio and bridge electrically an energy storing inductor, an output diode and a conduction switch of a power-factor corrector. The leaking inductance of the first coil set generates a back electromotive force to make the conduction switch in a zero current switching condition. An energy conversion circuit is provided to store reverse energy according to the coil ratio of the second coil set and the first coil set and reclaims the energy to an output capacitor of the power-factor corrector while the output diode generates a reverse recovery condition. Thereby reverse recovery time of the output diode can be shortened.