Abstract: Using gas geology theory,the gas content in No.3 coal seam of Mayixi No.1 shaft was analyzed qualitatively and quantitatively from three aspects,buried depth,thickness,metamorphic degree of the coal,surrounding rock of the coal and geological structure.It was concluded that the coal seam thickness,metamorphism degree,surrounding rock sealing and geological structure were the main geological factors which affected the gas content in No.3 coal seam of this mine.