Abstract: In order to analyze the distribution law of spontaneous combustion risk area in the working face of gently inclined coal seam when downward ventilation is adopted, a mathematical model of fluid seepage in inclined mining area is constructed, and the spatial distribution characteristics of oxygen concentration and temperature field in the downward-ventilated mining area are simulated by using Computational Fluid Dynamics（CFD）for the different spontaneous combustion conditions of the coal left in the mining area and validated by an engineering test in the No.8₁ seam of the Wenjiazhuang Coal Mine in Shanxi Province.The results of the study show that the fire-air pressure effect in the goaf increases significantly with the increase of spontaneous combustion tendency of the coal remains in the goaf, and the difference in the width of the oxidized zone between the inlet side and the return air side of the goaf is gradually reduced when downward ventilation is used.According to the engineering profile of the study area, the starting positions of the suffocation zones in the goaf corresponding to the inlet and return air sides as well as the middle of the working face were determined, which are about 200 m, 290 m and 175 m away from the working face, respectively.The measured data are consistent with the calculated results when the simulated fire source power is 65 W/m².