Abstract: In order to research the performances and internal flow characteristics of vortex pump, the vortex pump suction, head and cavitation principles were illustrated, and the fact that qv-NPSH performance curve is falling parabolic was obtained after experiment on the vortex pump (32WB8-12) prototype and measurement of flow field in chamber with 5-hole spherical probe. Based on the simulation of the three-dimensional internal flow within vortex pump utilizing RNG k-ε turbulence model, the certain fidelity and accuracy of the numerical simulation results were verified by comparing between simulation and experiment. From these results, the conclusion is that the internal flow in vortex pump mainly consists of through flow, and the forced vortex is the main flow characteristics in the impeller region, and the flow in volute is similar to the combined vortex with backflow, circular flow and free vortex, which is non-axisymmetric unsteady flow with quite high turbulence intensity, and all these lead to the relative low efficiency of the vortex pump.