A switching charging circuit works by receiving an input voltage and then correspondingly outputting an output voltage to a battery. Within a standby duration, to assure that there is sufficient voltage provided for turning on switches in a switching circuit alternately when the switching charging circuit works in the charging duration again, a bootstrap capacitor is charged by a supply voltage. When the bootstrap capacitor is charged, a reverse current is generated by the battery and the reverse current flows towards the input end of the switching charging circuit. In addition, by means of the circuit configuration of this switching charging circuit, the reverse current originally flowing towards the input end of the switching charging circuit can flow back to the battery or to a system load.