A control circuit of an electronic device comprises a circuit substrate, a plurality of welding pads, a processor and a wire switcher, wherein the plurality of welding pads are equipped in a footprint area of the circuit substrate and coupled to a connector which receives a plurality of control signals, and the amount of pins of the connector is not larger than that of the welding pads; the processor is equipped on the circuit substrate and connected with a plurality of signal sending and receiving wires; and the wire switcher is equipped between the footprint area and the processor and selects connecting modes of the signal sending and receiving wires with the welding pads according to modes of the connector.