Abstract: In order to study the internal cavitating flow in centrifugal pumps, the steady numerical simulation of the three-dimensional cavitating turbulent flow in the flow-passage of a centrifugal pump was numerically simulated by using the cavitation model and two-phase flow model provided by software Fluent.Based on the simulation results concerning the feature of both liquid-phase and cavity-phase flow, the region and the degree of cavitating occurred in the flow passage of the centrifugal pump under design working condition were predicted.The pressure distribution on the blade in the process of cavitation was analyzed and the internal characteristics of cavitation flow in the flow passage of a centrifugal pump was revealed, so that the performance of a pump could be estimated, which can be provide some basis for the prediction of cavitating properties for a centrifugal pump under design working condition.