The invention provides an outburst coal bed hydraulic phase change cracking cross-cut coal uncovering method, which is applicable to high-gas-outburst coal bed cross-cut coal uncovering operation. The minimum normal distance from the cross-cut coal uncovering working face to the coal bed is greater than or equal to 7m position, a plurality of holes are respectively drilled in the coal uncovering region, a conventional capsule hole sealing coal bed water injection technology is adopted for injecting water into the coal bed through the drilled holes, after the water injection completion, a conventional refrigeration freezing technology is adopted for freezing the coal bed around the water injection hole, in the freezing process, free water in the coal bed is gradually converted from the liquid state into the solid state, and the volume of the water expands for 9.1 percent in the phase change process; after the freezing completion, the freezing coal bed absorbs the underground environment head and gradually thaws. After the freezing thawing completion, the water injection hole and a gas extraction pipeline are connected for gas extraction, or the gas extraction drilling is implemented on the coal bed in the phase change cracking region for gas extraction. When the coal bed gas content is less than 8m<3>/t, the gas extraction is stopped, the water is injected into the water injection hole again, the secondary freezing of the coal bed is completed, and then, the coal bed is uncovered according to a conventional coal uncovering method.