An electronic device, includes a USB interface, a processing unit, a master-slave select triggering circuit, a controlling unit, a selection circuit and a switching circuit. The master-slave selection triggering circuit including an input port, a first output port and a second output port. The master-slave select triggering circuit is used to detect the type of external electronic devices connected to the USB interface, if the external electronic device is a master device, the first and second output port output a slave triggering signal, the controlling unit switches off the switching circuit t and the selection circuit selects the processing unit into slave mode; if the external electronic device is the slave device, the first and second output port output a master triggering signal, the controlling unit switches on the switching circuit and the selection circuit select the processing unit into master mode.