Abstract: For impellers without splitter blades and with splitter blades,the unsteady computational fluid dynamics method,large eddy simulation (LES),is applied to study the whole three dimensional flow field in centrifugal pumps, and the characteristics of flow field and noise are analyzed and compared.It has been shown that the interaction between impeller blades and volute tongue induces strong pressure fluctuations on blade surfaces.For impeller with splitter blades,although some local pressure fluctuations on main blade surfaces are increased,the pressure fluctuations on splitter blade surfaces remain at a lower level.At the same time,the pressure fluctuations on the pump inlet surface are decreased effectively,but the pressure fluctuations on the outlet surface are enlarged.Taken the blade surfaces as radiant resources,the noise features of dipole for the two types of impellers are compared.It is the splitter blades that change the distribution of acoustic energy in frequency domain,thus the OASPL is effectively reduced.