Abstract: In order to find accurately the principal factor that influencing index gases production under experimental conditions,formation amount of Wenzhuang coal index gases and the slope incidence degree of experimental initial temperature,temperature rising rate,dry air flow and coal quality are calculated.The results show that the initial temperature is regarded as the critical factor which affects the index gases producing,dry air flow rate and the weight of coal sample take the second place,and the temperature-programmed rate has the least effects to the index gases producing.