Abstract: Based on the semi-infinite body theory, the mechanical solution model of floor failure depth of inclined coal seam is established, and the maximum floor mining failure depth of inclined coal seam is calculated. Taking the mining geological conditions of No.10 coal mine of Pingdingshan Coal Group as the project background, based on FLAC^3D numerical simulation software, the numerical simulation is carried out on the characteristics of mining floor failure in 22300 working face. Research shows that the floor mining plastic failure zone is roughly a “ladle” distribution form whose bottom is towards the stop line side, and the mining floor reaches the maximum failure depth for the first time, with the peak being 15 m when advancing distance equals to the inclined length of working face. The displacement sensor method is used to measure the floor failure depth. The floor displacement monitoring curve shows that the maximum depth of floor mining failure is 14 m to 16 m, which is consistent with the theoretical calculation and the numerical simulation results.