Abstract: In order to master the abnormal gas emission reasons of 3908 fully-mechanized mining face in Zhaiyadi Coal Mine, we summarize that the gas emission of adjacent layer accounts for 79.59% to 90.26%, average 84.92% at working face. Through measuring gas parameters of the adjacent seam, we analyze the gas emission law in adjacent layer and obtain that No.6 coal seam is the main reason which makes an effect on the increase of gas emission at fully-mechanized working face. The test results show that the lithology of the upper and lower floor of coal seam, the coal's desorption characteristics to gas and the coal's specific surface area are the main factor which lead to abnormal gas occurrence by laboratory tests.