A resonant AC/DC converter. An input end of a half bridge rectifier circuit is connected to an alternating current power supply. A clamping surge protection circuit is connected to the half bridge rectifier circuit in parallel, and is connected to a resonant capacitor in a resonant DC/DC conversion circuit in parallel. When a voltage of the alternating current power supply is greater than a voltage of a bus capacitor, the clamping surge protection circuit is configured to prevent a surge signal entering the resonant DC/DC conversion circuit. When the voltage of the alternating current power supply is less than or equal to a voltage of a direct current bus, a voltage of the resonant capacitor is clamped. The resonant DC/DC conversion circuit performs electric energy conversion on the pulsating direct current that is output by the half bridge rectifier circuit, and then performs output.