Screen internals were used in a two-dimensional two-stage internal loop airlift reactor (ILALR). The influence of screens on the hydrodynamics and mass transfer characteristics in the two-stage ILALR, including gas holdup, mean bubble diameter, bubble rise velocity, and volumetric mass transfer coefficient (K(L)a), have been experimentally investigated. It is found that screens can efficiently break bubbles up. Radial bubble velocity distribution is more uniform when screens are installed. Mean bubble diameter with smaller screen pores seems smaller and slightly increases with the increasing of superficial gas velocity U-g. A larger gas holdup and K(L)a can be obtained when a suitable screen is mounted. The variation trend of overall gas holdup and interfacial area a with U-g is similar. A nearly constant liquid-side mass transfer coefficient (K-L) is found. The empirical correlations for the overall gas holdup and K(L)a have been proposed, which fit the experimental data well.