This study addresses the oil trapping phenomenon in the operation of external meshing gear pumps by proposing a design of unload groove gear pumps with optimized tooth profiles, based on performance requirements and design specifications. The internal flow field of the gear pump is characterized using a standard turbulence model, and computational fluid dynamics (CFD) is employed to model and simulate unload groove gear pumps with different tooth profiles. Based on the analysis of the internal flow characteristics and pressure distribution, the optimized unload groove significantly alleviates the oil trapping issue. Among the tested tooth profiles, the high-tooth profile demonstrates the best performance, achieving optimal flow characteristics and volumetric efficiency with minimal increase in axial load when combined with the unload groove. This study highlights the critical role of tooth profile optimization in improving the performance of external meshing gear pumps and provides valuable references for gear pump design and analysis.