Abstract: To achieve stable control of the electromagnetic performance stability of electromagnetic functional structures, shorten the development cycle, and reduce costs, this study establishes a parametric electromagnetic simulation and analysis model for typical curved-surface electromagnetic functional structures. Through simulation calculations, the influence of multiple parameter variables during the manufacturing process on their electromagnetic performance is systematically analyzed, including factors such as deviations in the electromagnetic parameters of raw materials, deviations in part structural dimensions, and overall structural deformation, and the radar cross-section (RCS) deviations caused by each factor are quantified. This study identifies the influence laws of each factor on electromagnetic performance, sets up an analytical method for controlling electromagnetic performance stability, and offers a theoretical foundation for the quality control of electromagnetic functional structures. The results show that deviations in the electromagnetic parameters of the skin have a significant impact on the fluctuation of high-frequency electromagnetic performance, while deviations in the electromagnetic parameters of the electromagnetic core materials have a significant impact on the fluctuation of electromagnetic performance in the broadband range, with the maximum RCS deviation reaching 3.57 dB; Of the structural dimension deviations of parts, the maximum RCS deviation resulting from changes in part thickness reaches 1.04 dB; Bending deformation of the curved-surface structure has a significant impact on low-frequency performance, with the maximum RCS deviation being 2.29 dB; the control of the electromagnetic parameters of raw materials is the top priority for ensuring the electromagnetic performance stability of the overall structure.