According to the operation status of the laboratory reciprocating compressor test device,a reciprocating compressor automatic monitoring system was designed based on S7-300 PLC, host computer,touch screen and inverter configuration.The fuzzy PID control algorithm and the frequency conversion were adopted in the control part, they worked together to achieve a stable output of pressure.The structural composition, hardware and software design flow of the system, simulation of fuzzy PID algorithm in MATLAB and frequency conversion speed regulation technology were discussed in detail.The actual operation results show that the monitoring system can automatically monitor the thermodynamic performance parameters and fault conditions during the movement of the compressor. The simulation results show that the response of the fuzzy control system is faster and more stable, the stability of the outlet pressure is improved, which greatly improves the reciprocating compressor use efficiency.