Abstract: By analyzing danger source associated with mine gas explosion, the evolution model GEFRPN of gas explosion based on Petri nets was constructed combining Petri nets theory and the evolution of gas explosion, and the conclusion was obtained: from reasoning process of evolution model of gas explosion, changes of confidence level of danger source in evolution process of gas explosion can be seen clearly, and so the function of each danger source in evolution process of gas explosion can be obtained. The importance of danger source to gas explosion can be analyzed by reasoning process and Petri nets diagram, so as to take early measures to avoid gas explosion accidents. The evolution model of gas explosion introduces confidence, and the calculation results have fuzziness, overcomes insufficient of fault tree method which has the results inconsistent with the actual situation.