Abstract: With the increase of the mining depth of coal seams, gas disasters have gradually become an important factor affecting mine safety production in the mining of steeply and ultra-thick coal seam in China; at the same time, due to the special geological conditions of the steeply inclined and extra-thick coal seam and the particularity of the mining process, the difficulty of gas control in its horizontal slicing working face increases.Therefore, based on the west working face of No.43 coal seam at +575 m level in Wudong Coal Mine, the source of gas emission from the working face was analyzed and the amount of gas emission was predicted; the gas stereoscopic drainage technology combining pre-drainage of long borehole along coal seam, buried pipe drainage in goaf, high-level borehole drainage to roof, and lower coal pressure relief interception drainage drillings were proposed. The results show that the gas in the west working face of No.43 coal seam at +575 m level mainly comes from the gas emission of the slicing working face and the lower coal pressure relief; the pre-drainage rate of gas in the working surface is 42.1%, and the drainage reaches the standard; in the process of stoping in the working face, the gas emission in the air inlet lane is maintained at 0.5 m³/min, and the gas emission in the return air lane has a decreasing trend, the gas concentration in the corner of return air is within a reasonable range and the gas extraction effect is relatively ideal during the mining process.