Abstract: Based on the energy theory, the transient energy variation of the gas outburst was analyzed, a positive effect mathematical physics model of the coal an d gas outburst including the coal and rock elastic energy and gas expansion energy and a negative effect model of coal and rock resisted gas outburst energy was esta blished.According to the coal and rock stress-strain test, the relationship between the force and deformation value of the coal and rock at different deformation stages W as obtained.With the positive effect and negative effect coupling models, the critical gas pressure value to cause the coal and gas outburst under different coal structure combined conditions in Sihe Mine was calculated.The results showed that under the other similar conditions, when the percentage of the soft coal increased, the critical gas pressure value would be reduced with exponential form and the possibility of the coal and gas outburst occurred would be increased.The application of the method could rapidly judge the critical value of the coal and gas outburst occurred and thus the effective measures could be conducted.