In order to research the hydraulic performance of the post position S-shaped shaft outlet conduit under the influence of circulation, the hydraulic performance of the post position S-shaped shaft pumping station under different blade models and different blade angles was simulated with commercial CFD software, and the experiment results were compared with the CFD results. The analysis of hydraulic performance of S-shaped outlet conduct showed that the inner flow field was strongly affected by the residual circulation of guide vane, the coefficient of hydraulic loss was no longer a constant, but a variable which was related to flow field. By comparing the relationship of the average swirl angle in the inlet and the hydraulic loss coefficient of the outlet conduit, it was found that an optimal average swirl angle existed for hydraulic loss coefficient. And the optimal average swirl angle was about 4°~5.3° for two different blades models, and the hydraulic loss coefficient was 1.62×10-4m·s/L. By analyzing the static pressure and total pressure distribution curve, the conclusion below can be drawn: the mainly reason for the hydraulic loss was average swirl angle value at the small discharge, on the contrary the reason for the large hydraulic loss was velocity at large discharge. After the water flowing through the second corner, most of the kinetic energy is recovered. The research result gave a good suggestion for the design and optimization of pump station.