A new method has been developed to reduce ground subsidence and deformation caused by mining ultra-thick steep coal seams. By slicing the coal seam at an angle and mining upwards, the movement of the surrounding rock layers is controlled, resulting in less deformation and a smaller subsidence angle. This method has been tested through simulations and experiments, showing a reduction of 5°–10° in the subsidence angle. A prediction model based on the mining influence angle can help estimate surface movement and deformation. The method has been successfully applied in a mining area, producing the desired outcome.