Abstract: On the basis of analyzing the layout and overall design of the ventilation system, a remote online monitoring system based on PLC is designed to complete the selection of controllers and sensors. Then the design principles of the two functional areas of the entire system are analyzed, namely, underground control monitoring and ground early warning disposal. A 485 communication network framework is built underground to realize multi-parameter measurement of ventilator system, such as the power supply parameters, equipment vibration, environment and equipment temperature, wind direction and wind speed, air negative pressure, gas concentration, etc., and to realize real-time monitoring of underground pictures; then they are transmitted to the ground through Ethernet, and functions of multi-parameter equipment status display, historical data query and early warning disposal can be realized by the upper computer. The practical application of this system is of great significance for improving the safety and stability of underground ventilator system, quickly locating and handling the fan system faults, and ensuring the safety of personnel and equipment.