Abstract: Based on the plasma arc micro casting and forging additive manufacturing process, the structure for traditional manufacturing was optimized by extracting mechanical and geometric characteristics, promoting uniform heat transfer, and minimizing residual stress as much as possible to ensure the stability of supports. 15-5 PH steel was used as the raw material of the experiment, through the printed piece’s chemical composition, microstructure, material-level tensile test, scale-down structural component defect detection and static test, the effectiveness of the design of scale-down structural components in optimizing the process adaptability was explored. The results show that the tensile and yield strength performance of the printed piece at room temperature and high temperature is comparable to that of forged bars, and the direction difference is not obvious. Further, the surface and internal defects of the scale-down structural components were characterized and analyzed by means of fluorescent penetrant and digital radiography, and the certain static loads were applied to the complex and weak parts of the scale-down structural component design for assessment. This work has certain reference significance for achieving optimization of more complex geometries and extending to other types of parts.