Abstract: Based on the gas data and geological survey information measured at each working face in No. T 86 mining block of Zhuianzhuang Mlinefeld as the basis ,the X-ra difraction analysis,microsection obsevation and other means aswell s the gas geolog theary were aplied tothe analysis and study on th gas ocurence law and the main infuence factors of the nagma erosion zone in No. 8 seam of Zhuianzhuan Mlinefed. The study hed that the magmatic ock inruded in the seam was a dlorte porphyite. The intrusion of the magmoatic rock and huge extensional fults would have high nfuences to the gas ocurenceof the seam.The ticker te magmatic rock vas,the stronger baking function would be to the seam and the more secondary gas generton would be. But under the funcion of the huge extensional faultsthe absoute emission voume of the sean gas would be a negative corelaton to the ticknes of the magmnatic ock.When the thckness of the magna was 2m.the gas emission volume would be 0.72 mn3 min.when the thickness of the magma was 14 m,the gas emission voume would be 0.32 m131 min. The mudstone of the seam roof and seam depth would have less influence to the gas formation of the seam.