Abstract: According to the characteristics of urban flood protection and drainage pump stations, two sets of dividing tubular pumping systems with symmetric aerofoil blade were developed. The three-dimensional fluid flow inside a diving tubular pumping system on dual-directional operation was described using computational fluid dynamics (CFD) technology. The effect of bulb section on the hydraulic performance of pumping system was analyzed, which included the hydraulic loss of bulb section, the internal flow of guide vane and the hydraulic performance of “S” shape impeller vane. Verification and analysis were done to the effectiveness of the numerical simulation results by model test. The results demonstrated that the internal flow pattern of guide vane was steady in the reverse operation conditions, while the flow pattern became turbulent, flow deviation and vortex were appeared in 4 and 5 m3/s of the main operation conditions. The hydraulic performance of pumping system in reverse operation conditions was better than that in main operation conditions, and axial force of impellers in which was smaller than that in reverse operation conditions. By comparing the comprehensive property index of two sets of pumping system, structure size of pumping system provided a reference for diving tubular pumping device. Diffusion angle of guide vane was 3°, the length of bulb and pumping system was 2.43 and 13.45D, respectively, and the diameter of bulb was 0.46 D. Bulb has streamlined tail and five supporting parts.