The invention provides a power supply control circuit which comprises a first power supply circuit used for supplying power to a universal serial bus device when a mainboard is started. The first power supply circuit comprises double diodes and a first electronic switch. The first input end and the second input end of the double diodes are respectively connected to a first power supply and a second power supply, the output ends of the double diodes are connected to the first end of the first electronic switch, the second end of the first electronic switch is connected to a third power supply,and the third end of the first electronic switch is connected to the universal serial bus device. When the mainboard is started, the first power supply output and the second power supply respectivelyoutput a first voltage and a second voltage to control the output ends of the double diodes to output the first voltage, the first voltage controls the first electronic switch to be switched on, and the third power supply supplies power to the universal serial bus device by outputting the second voltage. Therefore, the electronic switch can be prevented from being damaged due to too low power supply voltage, and the normal operation of the universal serial bus device is ensured.