Abstract: With the increasing of exploitation intensity, coal mine gas burning or explosion ignited by rock friction have occurred time and again. By the experimental study about progressive friction of rock roll，some conclusions were drawn that the maximum flash temperature is proportional to the square root of relative friction velocity; the ability to ignite methane by hot streaks is greater than by hot particles; the ignition capability positively correlates with the hard framework grains such as quartz, rock fragments and feldspar. In addition, combined with case analysis, it was drawn that the methane ignited by roof rock friction generally occurs during the periodic weighting and in the position of the bracket rear obliquely upward.