Abstract: Abstract: Based on the occurrence conditions of multi coal seam group in Wang Jiazhai coal mine, the necessity of mining 8# coal seam as a protective layer on the 11# coal seam is discussed. The gas emission status, characteristics and influencing factors during the mining of the upper protective layer 8# coal seam are analyzed, and the gas extraction technique of the protective layer on the close seam is studied. Dynamic pressure relief gas, roof drilling to extract seam gas in the overlying seam and underground gas drainage in goaf to extract goaf gas. Through the transportation lane and the return air lane of the protective layer, the protective layer is drilled and pre pumped to effectively control the gas of the protective layer, so as to ensure the normal production of the working face, and the co production of coal and gas is realized.