The effects of gas velocity, liquid velocity, redistributor and their free surface area on bubble properties （size, rising velocity, size distribution） and mixing characteristics (mixing time, circulation time) were studied in an internal airlift bubble column. Bubble properties were measured by resistivity probe method, and mixing characteristics were obtained by salt-base impulse method in air-water system. The empirical correlations between bubble properties, mixing characteristics and various operating parameters were proposed. The disk type redistributor was more effective to redisperse coalesced bubbles than the perforated plate type. Especially, the disk type with 19.5% free surface area had given the best result.