<p>The performance of a waterjet pump directly determines the overall propulsion efficiency and energy consumption level, making its optimization a critical link in enhancing economic efficiency and power output. This study focuses on the optimization of a waterjet pump using a three-dimensional inverse design method. The blade geometry was parameterized using the streamwise blade loading distribution and the spanwise circulation distribution from hub to shroud as the primary design variables. Four distinct variable-circulation distribution patterns, based on quadratic function parameterization, were developed. A comprehensive numerical analysis was conducted to evaluate overall performance, pressure pulsations at the impeller inlet and outlet, and unsteady excitation forces. Results indicate that circulation unloading at the shroud yields the minimum excitation force magnitude. Subsequently, based on the shroud-unloading circulation pattern, the influence of loading parameters on both the internal flow characteristics and external performance of the propulsion pump was systematically examined using a methodology combining orthogonal experimental design and single-factor analysis. An optimized impeller configuration was developed by implementing rear-loaded distribution at the hub and front-loaded distribution at the shroud. The final optimized impeller achieved a substantial hydraulic efficiency enhancement of approximately 1.41 % compared to the baseline design. The outcomes of this study establish a robust theoretical framework for the optimized design of waterjet pumps.</p>