Abstract: In order to solve the problems of low capacity, short communication distance and high wiring cost of wired bus communication node of sensor layer in traditional coal mine monitoring system, a communication system of wireless sensor layer for mine based on LoRa was designed to realize full coverage of monitoring regional network. The system gateway and terminal communication module design, terminal network access mechanism, communication address management, gateway capacity and channel allocation management, channel division and roaming mechanism are introduced in detail. Field experiments show that the designed system has the advantages of flexible networking, long communication distance and high link reliability, which can meet the demand of wireless communication of sensing layer in underground coal mine.