A charging device switchable between a first charging current and a second charging current includes a USB port and an identification signal providing circuit. The identification signal providing circuit outputs an identification signal to the electronic device when the electronic device is first coupled to the USB port. The electronic device determines whether the charging device matches the electronic device or not according to the identification signal. The electronic device is recharged using the first charging current when the charging device does match the electronic device, and the electronic device is recharged using the second charging current when the charging device does not match the electronic device.