The flow-ejecting self-priming centrifugal pump is a special kind of fluid machinery,which is an assemblage with jetting nozzle and centrifugal pump.It means that the pump can be improved cavity characteristics and suction head with some sacrifice of a part of efficiency.Based on CFD technology,a flowejecting self-priming centrifugal pump named XJWm/3BH was selected to simulate the steady and unsteady flow field in gas-liquid two phase flow and explore the characteristics of the pump to give a designed principle.The gas volume fraction(GVF)αg in pump inlet were set up 5%,10%,15%and 20%,respectively and bubble diameter was set up 0.1mm.After gas-liquid two-phase flow field numerical simulation based on single phase calculation was convergence with RNG k-ε turbulence model,the gas-liquid volume fraction distribution of impeller and jet inside can be gotten.The results show that when the αg was below the value of 0.05,pump performance did not change obviously and head decreases only 2m or 3m.When the αg was over the value of 0.05,head was almost halved.Jet,the impeller and other flow components were filled with gas destroying the continuity of flow in those flow conditions.In the part of jet device between 20mm and 90mm,the liquid phase velocity was larger than gas phase velocity,which the deviations were between 1m/s and 2m/s.When L was between 90mm and 150mm,it was just the opposite and the deviation is 4m/s.