A Universal Serial Bus (USB) charging circuit for a computer includes a USB interface, a USB power terminal, a standby power terminal, a switch unit, a IC chip, and a control unit. The control unit disconnects the USB interface from the standby power terminal when receiving a high voltage level from the system power terminal or a first control signal from the IC chip. The control unit connects the standby power terminal supply to the USB interface when receiving a second control signal from the IC chip and the first switch signal from the switch unit; the control unit disconnects the standby power terminal supply from the USB interface when receiving a second control signal from the IC chip and the second switch signal from the switch unit.