Abstract: In order to solve the problems of PLC easy damage, high equipment price and difficult maintenance in practical training and teaching. In this paper, a PLC simulation communication system based on 51 microcontrollers is designed, and the host computer is connected to the PLC simulation environment and communication board to realize the real-time control of the external load by the PLC simulation system. This paper elaborates on the overall scheme of the system, circuit design, host computer development and communication protocol, and verifies the practicability and stability of the scheme through debugging cases. The system has the advantages of low cost, high compatibility, and easy expansion, and is suitable for a variety of PLC training and teaching scenarios, and has good promotion value.