The present gas monitoring system for tunnel has many disadvantages, and it is urgent that multinetwork integration, informatization and intelligentialization of monitoring system be realized. Hence, the security monitoring system for gas tunnel based on Internet of things is established, which is functionally divided into 3 layers, i.e. perception layer, transport layer and application layer. And then the key technologies, i.e. wireless sensor network, personnel location, wireless methane monitoring system, MIMO wireless transmission technology, intelligent video system, SMS alarm system and blasting monitoring system, that used to realize overall monitoring on status of environment, personnel and equipment are studied. Finally, the applications of new equipments, such as portable methane detection and alarming device and intelligent gas alarm miner's lamp are analyzed and summarized. By adopting the monitoring system mentioned above, the overall perception of gas tunnel, wireless sensor network, mobile and fixedpoint monitoring of gas, accurate location of personnel, closure of blasting personnelmachinering, and remote and multilevel and multiplayer monitoring have been realized. The informatization and intelligentialization of the tunnel construction, and the scientific and effective monitoring and risk warning have leveled the security monitoring of gas tunnel.