Abstract: To improve the operational efficiency and stability of small and medium-sized vertical submersible pumping devices, this study focuses on the standardized design and application of outlet flow passages. Based on computational fluid dynamics (CFD) simulations, the hydraulic performance of the pump device under different design schemes was compared and analyzed by varying parameters such as the equivalent diffusion angle, outlet flow velocity, and outlet section size. The results indicate that when the equivalent diffusion angle of the outlet flow passage is 12°, the outlet flow velocity is 1.0 m/s, and the outlet section size is 1.84 m×1.84 m, the pump device achieves its highest efficiency of 70.44% with relatively low hydraulic loss. Compared to the traditional outlet pipeline design, the standardized outlet flow passage reduces outlet velocity and hydraulic loss, while expanding the high-efficiency operating range. These findings provide a theoretical basis for the standardized design of outlet flow passages in small and medium-sized pump stations, offering significant application values for promoting energy conservation and high-quality construction in such facilities.