Cavitation is the main factor that causes reliability problems in centrifugal charging pumps (CCPs) in nuclear power plants. In this study, the cavitation-induced unsteady flow characteristics of a CPR1000 CCP were investigated by numerical and experimental methods. The vapor distribution in the impeller, velocity fluctuation, and pressure fluctuation results in the time and frequency domains were considered for several typical monitoring points in the impeller and volute. The pressure fluctuations in the impeller occurred at an impeller rotating frequency of fR and its integer harmonics, whereas those in the volute mainly occurred at an impeller blade-passing frequency of fB and its integer harmonics. The absolute error between the simulated and measured NPSHr was 3.6%, and that between the calculated and measured head was 2.9%, validating the simulation of the cavitation performances of a CCP.