Abstract: Methane explosion triangle method, which is commonly applied to judge the explosion risk of mixed inflammable gases in the mine fire district, considers only the main component gas. In practice, the method does not consider the influence of the temperature in the mine fire district. In this paper, an engineering calculation method for determining parameters of mixed inflammable gases is presented. Explosion limits could be decided by Le Chatelier method and corrected by measured temperature in situ of the fire district. Critical oxygen concentration for explosion is decided by a new triangle illustration method. This mixed gases explosion triangle analytical illustration could be applied to the mine fire district, especially to long range mine fire district during closing and opening process to judge the explosion risk of mixed inflammable gases and to formulate measures for prevention.