Abstract: In this paper,based on the physical simulation results of coal and gas outburst under the condition of gas- solid coupling,the evolution process of temperature-pressure-stress during outburst was analyzed. Considering the con- servation of energy in the system,the real-time evolution of polytropic exponent in outburst process was discussed,and the calculation method of gas expansion energy in the polytropic process was derived. On this basis,the problem of en- ergy release in outburst process was discussed. The conclusions indicate that there are three types of stress changes in different parts of the coal body:initial decrease-fluctuating rise-stable rise type,initial rise-slight decrease-stable rise type and slight decrease-stable rise type. There are two types of gas pressure changes:initial decrease-fluctuating rise- stable decrease type and slight decrease type. The temperature appears as a single continuous decline process during outburst process. The relief stress zone and concentrated stress zone are the polytropic process of isothermal process-i- sobaric process-adiabatic process in the early stage of outburst,the mid-term is an isothermal process,and the late stage is the polytropic process of isothermal process-isobaric process. The increased stress zone is a polytropic process of isothermal process-isobaric process in the early stage of outburst,and the main stage is an isothermal process in the middle to the late stage. The original stress zone is a polytropic process of isothermal process-isobaric process in the early stage of the outburst,and it is an isothermal process-adiabatic process from the middle to the late stage. During outburst process,the release of elastic strain energy of the coal body mainly comes from concentrated stress zone and increased stress zone. The release of the elastic strain energy of various parts of coal body will show a phenomenon of first drop and then rise,and the elastic energy of each area will not be completely released at one time. The gas expan- sion energy released closer to the working face during the outburst process is greater. The release of gas expansion en- ergy is not a continuous process,but presents a stage of volatility,which is particularly evident in the later stages of outburst.