Abstract: In view of the problems of large thickness of coal seam, high gas content and inability to accurately master the overall extraction effect in layered mining working face of extra-thick flat seam, taking the stratified mining working face of extra-thick seam in Baijigou Coal Mine as the engineering background, by studying the gas occurrence law of extra-thick and high metamorphic anthracite coal, on the basis of the large amount and accurate determination of gas content of coal seam in different extraction periods and different strata on site, the study on the three-dimensional distribution of gas content in stratified mining of extra-thick flat seam was carried out.The results show that, on the strike, the more close to the working face cutting, the higher the residual gas content of coal seam; in the trend, the closer to the transport lane, the higher the residual gas content of coal seam; in the vertical direction, the residual gas content in the middle of the extra-thick coal seam is relatively high and the residual gas content decreases gradually along the direction of roof and floor. On this basis, the concept of three-dimensional distribution of residual gas content in extra-thick coal seam was put forward. The relationship model between residual gas content and extraction time of coal seam in different positions under the condition of three-dimensional extraction in extra-thick coal seam of Baijigou Coal Mine was established. Therefore, the system of mine gas geology management was supplemented and perfected, which provided scientific basis for guiding the layout of extraction borehole and determining the inspection target layer of extraction effect.