Road accelerated loading test equipment is an important device for making road surface test under dynamic load action, and making test and evaluation on road structure and road surface material. The paper analyzes structure and working principle of road accelerated loading test equipment, mainly researches hardware circuit design of control system. In order to realize real-time display of operational parameters, data communication between PLC and single chip microprocessor uses free port communication mode. The paper mainly introduces communication protocol and its realization method, and proposes partial key programs. Operation of road accelerated loading test equipment indicates the equipment has reliable operation, the control system has stable working, and the data communication system is simple and practical.