Abstract: With the advancement of lead-bismuth fast reactor (LFR) technology, characterized by high inherent safety and excellent thermal-hydraulic performance, electromagnetic pumps (EMPs) utilized for circulating liquid lead-bismuth eutectic (LBE) have garnered increasing attention. EMPs offer distinct advantages such as structural simplicity, high sealing integrity, and convenient flow control, making them ideal for the primary cooling systems of LFRs and space reactors. Leveraging the excellent electrical conductivity of liquid metals, EMPs generate Lorentz forces through the interaction between a traveling magnetic field and induced currents to drive fluid motion. To conduct an in-depth investigation into performance-influencing factors, a 3D magnetohydrodynamic (MHD) model was established using the finite element method (FEM) to solve the strongly coupled Maxwell’s and Navier-Stokes equations. A one-sixth symmetry model was developed to balance computational efficiency and accuracy, with the reliability of the numerical results ensured through rigorous grid independence verification. The study analyzed the coupled effects of electrical and structural parameters on EMP performance. Regarding electrical parameters, while the electromagnetic driving force increases quadratically with the input current, an increase in the number of slots and pole pairs reduces the synchronous speed, thereby weakening the driving capability. In terms of structural parameters, the influence of the annular channel width exhibits a non-monotonic trend due to the competition between magnetic reluctance and secondary resistance, revealing an optimal width of 4 mm for the current design. Furthermore, extending the central core length effectively mitigates longitudinal end effects and improves magnetic field uniformity, although the performance gain tends to saturate beyond a certain threshold. Adjusting the central core diameter requires a trade-off between magnetic flux density and eddy current preheating efficiency during start-up. Based on these findings, a design strategy involving the synergistic optimization of the core aspect ratio and the tooth-slot structure was proposed under strict engineering constraints, including a flow velocity limit of v＜2 m/s to prevent LBE erosion. Validation results demonstrate that at an input current of 155 A, the optimized EMP achieves a 44.2% increase in electromagnetic driving force, a 14.0% increase in output flow rate, and an improvement in overall efficiency of approximately 15%. This research provides a theoretical basis and engineering reference for the autonomous design of high-performance LFR primary pumps.