Abstract: In order to master the law of fracture making and the action mechanism of hydraulic fracturing in steeply inclined coal seams and provide technical guidance for on-site coal seam hydraulic fracturing technology, using laboratory experiment research methods, the laboratory true triaxial experiment was carried out with Wudong Coal Mine as the research object and three-dimensional stress and bedding of coal seam as the experimental variables. The results show that the effect of hydraulic fracturing mainly depends on the process of pressure holding to overcome the filtration effect. When the bedding is perpendicular to the direction of the maximum principal stress, the filtration effect decreases with the increase of three-dimensional stress, which is conducive to hydraulic fracturing. When the bedding is parallel to the direction of the maximum principal stress, the filtration effect increases with the increase of three-dimensional stress, which is not conducive to hydraulic fracturing. The research results provide a reference for the hydraulic fracturing technology of steeply inclined coal seam and improve the research content in the field of mine hydraulic fracturing.