Abstract: The operation performance of an air-liquid ejector was experimentally studied under different conditions. Results show that under the critical mode, the entrainment ratio decreases slightly with the increase of liquid-air ratio in the primary fluid, and when the liquid-air ratio varies from 0 kg/min to 0.2 kg/min, the entrainment ratio would be reduced by 5.9%-8.7% accordingly; whereas under the sub-critical mode, the entrainment ratio reduces significantly with the rise of liquid-air ratio, resulting in lowered entrainment performance of the ejector, and when the liquid-air ratio varies from 0 kg/min to 0.2 kg/min, the entrainment ratio would be reduced by 16.9%-29.3% accordingly. At the same time, both the critical back pressure and the critical pressure ratio decrease with the rise of liquid-air ratio, resulting in poor pressure-lifting performance; when the liquid-air ratio varies from 0 kg/min to 0.2 kg/min, the critical back pressure and the critical pressure ratio would be reduced by 0.006-0.010 MPa and 0.041-0.065, respectively.