Supersonic film cooling technology is widely used in active thermal protection of hypersonic aircraft. A numerical simulation method was used to investigate the effects of the Mach number at the cooling gas′s inlet, blowing ratio and the height of the spray seam on the supersonic film cooling characteristics for both flat and curved surfaces, and the effectiveness of film cooling was experimentally verified. Results show that regardless of whether the cooled wall is flat or curved, the supersonic gas film has good wall adhesion characteristics and can effectively cool the wall. In comparison, the cooling effect of supersonic gas film on curved surfaces is better than that on flat surfaces. Increasing the Mach number at the cooling gas′s inlet and blowing ratio can improve cooling efficiency. As the height of the spray seam increases, the film cooling efficiency increases and gradually reaches a constant value. When the height of the spray seam is large enough, the advantage of further increasing the height of the spray seam is not significant.