Abstract: According to the problem of high spontaneous combustion danger of left coal in the goaf of No.5101 coal mining face with the slicing mining in the easy spontaneous combustion and thick seam, with the site monitoring on the gas components variation of the goaf in the top and low slices and the spontaneous combustion experiments of the coal samples from the coal mining faces, the paper had a study on spontaneous combustion limit parameters of the goaf during the slicing mining an d the distribution law of heat dissipation zone, oxidization and heat accumulation zone, suffocative zone. The study showed that during mining the low slicing, the previou s suffocative zone of goaf in the top slice and the goaf of the low slice coal mining face would form two heat dissipation zone, oxidization and heat accumulation zone, su focative zone. The spontaneous combustion danger of the primary oxidized left coal would be highly increased after the secondary oxidization. Meanwhile, the width oft he spontaneous combustion danger area in the goaf would be increased over 100 m and the primary CO concentration would be rapidly increased. During the coal mini ng period, the nitrogen injection, leakage sealing at the two sides of the goaf, grouting and other fire prevention technical measures were conducted, and the effect inspect ion was conducted to ensure the normal mining operation of the coal mining face.