The Constrained Groove Pressing (CGP) process, belonging to the class of severe plastic deformation (SPD) techniques, is known for its ability to produce ultrafine-grained microstructures and improve the strength and ductility of sheet materials. Nonetheless, achieving stable formability during successive CGP passes remains a major concern. In this research, three-dimensional finite element analyses were carried out using the DEFORM-3D V11 platform to explore how primary process variables, including sheet thickness (s), groove angle (θ), and friction coefficient (μ) on the deformation behavior of AA5083 aluminum alloy. To assess formability, the die filling ratio (Rf) and the maximum compressive force (Ff) were employed as quantitative performance metrics. The Taguchi method was applied to design the simulation matrix, followed by an analysis of variance (ANOVA) to evaluate the statistical contribution of each factor. The signal-to-noise (S/N) ratio analysis was further utilized to identify the most effective parameter combination. The results indicate that optimal die filling occurs with a 2 mm sheet thickness, a groove angle of 45°, and a friction coefficient of 0.125, while the minimum pressing load corresponds to 1 mm thickness, 45° groove angle, and a friction coefficient of 0.1. These outcomes provide practical insights for the design and optimization of CGP parameters when processing AA5083 aluminum alloy.