Abstract: In order to study the symbolic associated gas during the oxidization process of the left coal in the mine goaf affected to the gas explosion, with the exper iment measurement conducted on the coal samples, the symbolic associated gas at the different temperature rising stage of the left coal was determined. Based on the GRI 3.0 methane combustion reaction mechanism of the Senkin in CHEMKIN, under the condition of the constant volume, the volume fractions of the gas and symbolic associated gas in the two stages of the acceleration and intense oxidation were set up and the gas explosion temperature, pressure, intermediates and key reaction ste p sensitivity coefficient were simulated and calculated. The results showed that with the volume fraction of the symbolic associated gas increased, at the acceleration 0 xidation stage, the explosion time was about 0.003 0 s in advance and the explosion pressure and temperature were increased by 0.012 MPa and 30 K individually. In t he intense oxidation stage, the explosion time was about 0.000 2 s in advance and the explosion pressure was increased by 0.007 MPa. The free radical OH volume fra ctions were steadily reduced at the two stages, thus the sensitive coefficient of key reaction step was highly reduced and could promote the gas explosion.