Abstract: In order to improve the data safety of the monitoring system, ensure the correct transmission of data and the execution of control commands, and reduce accidental faults, based on the transformation and commissioning of mine automation subsystem, the control process and data flow direction of the main fan monitoring system in Donglin Coal Mine are studied and designed; the control logic of the system is managed hierarchically, different working modes are designed for each man-machine interface equipment in the system, such as touch screen and upper computer configuration software, different permissions are assigned to the operation instructions, and the function is locked. At the same time, the safety level of PLC and the control process of the third-party platform interface are designed. The field application shows that this scheme enhances the stability of the system, reduces the potential safety hazards in data flow and control command transmission, and improves the safety and stability of the automation subsystem.