A PLC control method includes: transmit a first signal through a neutral wire and a path between the neutral wire and a differential signal processing circuit; transmit a second signal through a live wire and a path between the live wire and the differential signal processing circuit; and disconnecting the path between the differential signal processing circuit and the neutral wire or the live wire, conducting the differential signal processing circuit to a ground wire, and when a transmission rate of the ground wire is greater than or equal to a preset transmission rate threshold, transmitting the first signal or the second signal through the ground wire and a path between the ground wire and the differential signal processing circuit.