Abstract: The present invention provides an operating method for USB hub supporting role-switch function. The processing unit of the USB hub will transmit a control signal to the first electronic device having both the host mode and the device mode and connecting to the down stream port for changing the operating mode. Thereby, the electronic device is able to access a peripheral device connected to another down stream port. Alternatively, the electronic device can be accessed by the second electronic device having the host mode and connected to the up stream port.