<p>Magnesium alloys are regarded as the next-generation lightweight structural materials; however, their formability at room temperature remains limited. Hydromechanical deep drawing is an effective technique to enhance the formability of magnesium alloys, with pressure rate (the pressure increment per unit time) being a critical parameter influencing part formability. In this study, a finite element model of an AZ31B magnesium alloy cylindrical component was established to investigate the effect of pressure rate on wall thickness. Under constant process parameters, variations in wall thickness at different pressure rates were simulated, and the impact on minimum wall thickness, thickness distribution, and uniformity was analyzed. Additionally, a predictive equation for wall thickness uniformity of cylindrical parts was developed. Metallographic analysis and hardness testing were conducted to examine the microstructure and hardness distribution in different deformation regions under varying pressure rates, with a focus on explaining the relationship between hardness distribution and microstructure. This study provides insights into the hydromechanical deep drawing mechanism of magnesium alloys from both micro- and macroscopic perspectives, offering a theoretical basis for optimizing the forming process.</p>