Abstract: To improve the operation efficiency and stability of small and medium-sized vertical submersible pumping device, this paper focuses on standardized design and application research of outlet flow passage. Based on the computational fluid dynamics (CFD) simulation method, the hydraulic performance of different design schemes is compared and analyzed by changing the equivalent diffusion angle, the outlet flow velocity, the outlet section size and other parameters. The recommended design parameter combination of the outlet flow is proposed, and the purpose of the standardized design of the outlet flow is achieved. The results show 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 1.84×1.84 m², the pump device has the highest efficiency, reaching 70.44%, and the hydraulic loss is relatively small. Compared with the traditional outlet pipeline scheme, the standardized outlet flow passage scheme can reduce the outlet velocity and hydraulic loss, and can expand the high-efficiency operation range. The research results provide a theoretical basis and engineering reference for the standardized design of outlet flow passage in small and medium-sized pump stations, and have significant application value in promoting energy conservation and high-quality construction of small pumping stations.