Abstract: According to the preliminary parameters of Pizhou pumping station in East Route Project of South-to-North Water Diversion， and based on the method of 3D turbulence flow numerical simulation for inlet conduit， the influence of the control size of the shaft inlet conduit on hydraulic performance has been studied. The influence of conduit control size including length， width and height on the velocity distribution， weighted average angle at the conduit outlet section and hydraulic loss has been revealed， and the velocity distribution in the conduit has been analyzed. The research results indicate that the control size has comparatively obvious influence on the hydraulic performance for the shaft inlet conduit； the increase of the control size improves the hydraulic performance of the conduit obviously， and its influence is going to be gentle after the size increases to a certain value； the control size of the shaft inlet conduit for the Pizhou pumping station is reasonable， the flow in the inlet conduit contracts smoothly and uniformly， and the stream line layers are clear； and there is no improper flow such as separation or vortex in the conduit， and the hydraulic loss is little. The analysis results can provide a theoretical basis for the hydraulic design as well as the control size of the shaft inlet conduit.