In order to carry out real-time monitoring of the underground gas concentration, the coal mine gas monitoring system based on DSP and gas concentration sensor MQ-4 have been designed. Gas monitoring system is mainly composed of the main control unit, liquid crystal display, sensor and Ethernet communication module. After the signal is monitored by the gas concentration sensor, the collected data is transmitted to the DSP in the form of voltage. After the data is processed by DSP, the data is displayed on the 12864 liquid crystal display through the bus mode, and the data is transmitted to the upper computer by the DSP in the form of UDP data. Monitoring of gas concentration is achieved from underground to wells.