Abstract: The coal spontaneous combustion early-warning index is determined by the experiment of coal sample oxidation in 111300 fully-mechanized mining face in Xinji No.2 Mine. With the advancing of mining face, the changes of gas composition are recorded by the buried pipe in the gob. According to the division standard of “three-zone” of spontaneous combustion area and the concentration variation of O₂ and CO and combined with the changing laws of oxidation gas products of coal samples, the “three-zone” of 111300 fully-mechanized top-coal caving face are determined, the limit mining speed is also calculated, which provides the basic parameters for the fire preventing and extinguishing work.