The shot peening process can improve the fatigue strength of machine parts of aero structures. Due to the strength requirement of aircraft, the shot peening is widely used in the manufacturing process. Most of shot peening parts peened after penetrate inspection to ensure no defect and crack on the surface, and then peen the shots on the surface of machine parts to increase the fatigue life. During the first article verification period, the saturation curve has to be created. The peening parameters of mass production would base on the peening parameters of saturation point of the saturation curve. By using statistical methodology to analysis saturation curve of shot peening process, this study tries to find the relationship between saturation curve and relative peening parameters, such as peening time, air pressure. The results of this analysis can provide an efficient and economical approach for the process engineer and technician to develop the new shot peening process.