Abstract: In order to master thoroughly the different fire-extinguishing effects of N₂ and CO₂ on coal flame combustion,the self-developed experiment device of coal flame combustion was used to conduct the fire-extinguishing experiment on coal flame combustion under the condition of importing same flux N₂ and CO₂ gas fire-extinguishing agent for coal samples in Eight mine of Ping Dingshan coal mine,and the change laws of temperature of temperature field,index gas formation(O₂,CO and CH₄),heat release rate and flame image area obtained from the experimental stages of the coal flame combustion and smoldering extinguished were measured,The results show that:compared to the free combustion of coal,in coal flame combustion stage,flame out time,coal temperature rise rate,oxygen consumption,heat release rate as well as the speed of CO and CH₄ concentration decline in coal combustion with CO₂ much lower than that of coal combustion with N₂;meanwhile,the flame image area exponentially decline in coal combustion with CO₂,but the flame image area linearly decreases in coal combustion with N₂,In the coal smoldering extinguishes stage,the coal temperature,the speed of CO and CH₄ concentration decline in the coal combustion with CO₂ much higher than that of coal combustion with N₂,but the oxygen consumption and heat release rate are lower,It follows that CO₂ has greater capacity of extinguishing coal combustion compared to N₂.