Abstract: Based on the current cutting theory of centrifugal pumps with low specific-speed, the impeller diameter of pump MH-46-100 was cut three times, and the flow area of the model was divided with blocking non-structural hexahedron grid. The finite volume method was useed to disperse Reynold time-average Navier-Stokes equation. The RNGk-ε turbulence model and SIMPLEC algorithm were employed to simulate each model. The comparison between the result of the performance predicted and the current cutting theory for centrifugal pumps with low specific-speed was conducted. It was proved that the cutting theory was correct and the flow obtained based on the cutting theory was similar. It was also found that the efficiency will increase when the impeller diameter was cut. At last, the flow conditions of each model were analyzed and compared.