Abstract: In order to research the flow-head curve plunge caused by the cavitation of centrifugal pump,the standard k-ε turbulence model,homogeneous multiphase model and Rayleigh-Plesset equation were applied to simulate the cavitation characteristics in a centrifugal pump with specific speed of 59 under different conditions based on ANSYS CFX software.The results show that the numerical simulation result has the same trend with experiment result,and absolute error is 0.02%.The analysis of flow field shows that: the steep fall of flow-head curve is not only caused by the traditional cativation,but also mainly caused by the Vortex loss.As the empty bubble in the passageway increases to some degree,the liquid boundary layer separation happened,then vortex appears and vortex losses.While the vortex appears originally,it has an impact on the flow-head curve.When the bubble becomes more and the whole passageway is full of vortex,cavitation fault condition happens.It reveals the vapor-liquid tow-phase flow distribution within the centrifugal pump.