In view of problem that gas disaster causes serious hazards to coal mine production safety, four levels and influence factors and their weights of gas disaster evaluation index system were established by applying analytic hierarchy process, and disaster evaluation model was set up. Four main factors affecting gas disaster and three consequences severity index were proposed, and quantitative method and weights of these factors were studied based on the analytic hierarchy process, so as to quantitatively reveal main causes of gas disaster. The method has great significance to prevent occurrence of coal mine gas accident.