Abstract: This paper presents an experimental and numerical study of the flows in the inlet channel of a pumped storage plant intake based on hydraulic model tests on the inlet and outlet of the plant. We have developed a three-dimensional model using the RNG k-ε turbulence model and VOF method to optimize the open channel shape of primary design and eliminate the harmful flow circulations observed in the inlet channel. The optimized scheme of final recommendation increases the lateral diffusion angle of this design's inlet channel and installs a sill at the downstream end of the short diversion section that is located upstream of the diffusion and takes a lower bed elevation. Experiment shows that this end sill can effectively adjust the flow into more homogeneous velocity profiles at the cross sections and improve flow patterns in the inlet channel remarkably, completely eliminating all the flow circulations.