Abstract: Aiming at the problem that rock collision and friction can burn coal and gas in gob area when hard roof collapse,method of theoretical calculation and laboratory test are used to analyze chemical composition,energy conversion and the cause of the spark generated by the impact friction of rock in China Coal Xinji No.2 Mine.The experimental results show that quartz sandstone containing pyrite which can increase the probability of burning coal and gas in gob area.Rubbing 60 times under the pressure of 8 kN and 12 kN respectively, the temperature rises of the smooth surface and the rough surface are both between 1 and 2.1 degrees.The temperature rise of the rock surface is linear with the friction time (number of times), and is positively correlated with the roughness of the rock surface. Impact tests are carried out at different heights(0.9、1、1.5 m),the rock surface temperature is positively correlated with energy of the rock and the number of collisions. According to the above-mentioned influencing factors, the on-site defense measures such as deep-hole pre-splitting blasting, roof-oriented drilling and the upper-level corner buried pipe are given. The scene has not been exposed to spark ignition gob accident for a long time.