Due to the defects of low energy transfer efficiency and high residuary pressure in the water-air two phase jet pumps, the concept on the annular water-air self-excited oscillation jet is proposed to combine the advantages of annular jet and self excited oscillating jet. The conservation of momentum and continuity equations have been obtained based the theory of annular jet. The flow field of the annular water-air self-excited oscillation jet is numerically solved by using the Realizable k-ε turbulence model and the Euler multiphase model, respectively. The performance parameters of the annular water-jet self-excited scillation jet pump such as pressure ratio h, efficiency η and flow ratio q are calculated. The basic performance curve has been obtained as compared with an ordinary annular water-air jet pump. The unsteady fluid average velocity at the down nozzle has been calculated, and the pulse frequency has been obtained. The results show that the entrainment capability could be enhanced by the annular water-air self-excited oscillation jet as compared with the ordinary annular water-air jet and the average velocity of fluid at the down nozzle has a significant pulse frequency.