Air sparging is recognized as an effective way to overcome concentration polarization in membrane filtration processes. The mechanism of flux enhancement in the case of slug flow in tubular ceramic membrane is discussed in this Article. The region near the gas slug is divided into three different zones: gas slug zone, wake zone, and remaining liquid slug zone. Air sparging significantly increases shear stress and flow instabilities, and consequently lowers concentration polarization for the gas slug zone and the wake zone. A novel model based on hydrodynamics of air-liquid two-phase flow is developed to predicting permeate flux in such processes. The dimension less groups of filtrate resistance number and shear stress number are used to analyze the cake resistance induced by the concentration polarization, and, from these, the average permeate flux for air sparged ultrafiltration can be calculated. The model was tested by the ultrafiltration of T2000 dextran at different gas now rates with an external-loop airlift ceramic membrane reactor. The model is validated with experimental data with an error of 10%. Experimental results show that air sparging can enhance the permeate nux significantly.