Abstract: The digital upgrade and transformation of the coal mine safety monitoring system have significantly improved its safety and stability, but the operating environment, system software and hardware, human operation and other factors still lead to abnormal situation, such as data collection, data processing and network transmission, so it is necessary to set the fault self-diagnosis units in the key links of the system. According to the configuration characteristics of coal mine safety monitoring system and the actual requirements of operation and maintenance, the system is divided into three levels: perception layer, transmission layer and platform layer. In view of the problems existing in each level, the fault self-diagnosis module is studied and designed from the aspects of software and hardware, and the functions of each module are pointed out. The field application test shows that the hierarchical fault self-diagnosis technology can effectively improve the quality of information interaction and data transmission, and improve the reliability of coal mine safety monitoring system.