Abstract: In order to study spontaneous combustion characteristics of the first mining middle coal seam in Yilan Mine, guide and establish work of fire prevention and control in mine, through test methods, the study conducted industry analysis, total sulfur, coal spontaneous combustion tendency, the shortest period of spontaneous combustion, ignition point, explosive coal dust of middle coal seam, and established spontaneous combustion index system of first mining middle coal seam, through temperature oxidation experiments, the study tested toxic and harmful gases of oil shale precipitation, large sulfur content and large oxygen uptake of oil shale is key point in work of fire prevention and control in Yilan Mine, simultaneously proposed fire prevention methods with liquid nitrogen.