In order to ensure the safe mining of extra thick and spontaneous combustion coal seam No.13 in Jindi coal preparation plant, the method of buried pipe was used to real-time monitor the float coal thickness and oxygen concentration of working face No.1321. according to the monitoring results, the distribution maps of float coal thickness and oxygen concentration were dawned. On this basic, the spontaneous combustion zone was defined. the methods of controlling the air volume of the working face, spraying the fire proofing agent, injecting nitrogen, and injecting the yellow mud, etc., effectively prevent the coal spontaneous combustion accident in the goaf, realizing the safe and smooth mining of the working face.