Abstract: In view of problems of low measuring precision, bad stability and bad real-time performance existed in general gas monitoring system, and high cost of development and maintenance existed in gas monitoring system with high measuring precision, strong stability and real-time performance, the paper proposed a design scheme of underground gas monitoring system based on FPGA. It introduced design of hardware and software of the system in details.The result of simulation test showed that the system has characteristics of high monitoring precision, good stability, rapid response speed and low cost of debugging and operation.