The vertical stress of mountainous areas has controlling effect on gas occurrence of the coal seam below of it. The influence mechanism of depth, stress and permeability of coal seam under mountain were studied based on the Winkler elastic Foundation beam theory and seepage theory. At the same time, the enrichment mechanism of coal seam pressurized by overlying mountain was analyzed. The results shows that: (1) There is a significant strong correlation between the stress characteristics, permeability change rule of coal seam and the change of buried depth and surface elevation. (2) Under the action of vertical pressure of mountain, the stress and permeability distribution of coal seam show significant nonlinear characteristics. The stress is the greatest under the peak and the permeability is the smallest. (3) The initial gas content value is controlled by the permeability and the stress of coal seam in the situation. Under the guidance of the research results, Kuangou Coal Mine adopts the "large-diameter pressure relief drilling + small-aperture pre-drainage drilling method, leading the pressure relief mountain overburden coal seam advance area, pre-draining coal seam gas anomaly area, coordinated long distance + short distance high Drilling gas in the mined-out area to ensure the safe production of the mine. During the mining of the working face, no large-energy microseismic events with a power of more than 6 power level occur. The gas concentration in the upper corner does not exceed 0.50%, and the gas concentration in the return air flow does not exceed 0.22%. There is no gas anomaly, which effectively solves the problems of coal seam rockburst and gas emission at the working face of the mine. The research results can provide a theoretical basis for the rockburst and gas gushing in the overlying coal seam in the mountain.