In order to gain the inner flow field of flow-ejecting self-priming centrifugal pump, a flow-ejecting self-priming centrifugal pump equipped with a jet in the front of impeller inlet was chosen as the study object. The geometric model including all parts was built up by Pro/E software. The turbulence model chosen was RNG k-ε turbulence model and the mesh independence was checked by six meshes with different grid number. The external performances and the inner flow fields under seven different working conditions were simulated by CFX 14.0. The profiles, such as static pressure and velocity, were obtained. Then, the numerical results were compared with the testing results gotten on open test bed. The results show that the errors of head, shift power and efficiency between the simulation and the testing under designed condition are 2.63%, 6.16% and 14.29%, respectively. The simulating and the testing power curves are almost horizontal lines and change slowly when the flow rate is smaller than 3.5m3/h. The absolute velocity distribution between the nozzle and the line segment is axial symmetry. However, between the diffusion section and the impeller inlet, the upper velocity is larger than the lower velocity. And the velocity of the flow entering the impeller inlets is not uniform. The location, L=0.148m, is a critical location where the static pressure is the smallest and the turbulence dissipation rate achieves its maximum value. The numerical results provide a directly theoretical guideline for the pump design.