Abstract: Underground coal fire 90% is caused by the destruction of small coal mines. Among them, coal spontaneous combustion in the open-pit coal mine will occur and seriously affect the efficiency and safety of coal mine production when the mining is close to the goaf formed by the destruction of small coal mines. According to the occurrence conditions and characteristics of gas production and heat release in the process of the coal spontaneous combustion, this article presents a method for delineating fire area on the basis of the cavity detection by geological radar and temperature field inversion, and presents a hierarchy analysis model of weight of each element in factor set to be considered and a two level evaluation model by the weighted average of the development status and trend of fire behavior. In addition, based on the analysis of the fire behavior, the efficient and comprehensive extinguishing technology setting oxygen insulation, cooling, prevent recrudescence in one is proposed.