Abstract: In this paper, the difficulty of slag discharge and the low porosity of the high-gas soft coal in the underground coal mine are studied. The numerical simulation of the deformation and slag production of deep high gas soft coal under the combined stress is carried out by FLAC3D numerical simulation technology. The law of slag generation and deformation of deep high gas soft coal in the bedding layer is revealed, and the deformation characteristics and stress variation of the coal around the long hole in the bedding layer are analyzed. The numerical simulation study shows that the large-volume sudden collapse will occur after the critical condition of the stress balance of the coal body in the deep high gas soft coal bedding hole; the maximum deformation displacement of the drilling level is 1.22mm, and the maximum deformation displacement in the vertical direction is 10.7mm; along the radial distribution of the borehole, the vertical deformation of the coal around the hole shows a decreasing trend, and the vertical deformation is significantly larger than the horizontal deformation of the borehole. In the horizontal direction, the stress distribution of the coal body around the borehole increases first and then gradually decreases. The influence of the radial distance on the horizontal stress distribution gradually decreases. With the increase of the radial distance, the borehole The stress distribution of the coal body gradually decreases, the stress of the coal body at the wall of the borehole appears the maximum, and the stress value in the vertical direction is the largest.