The oxygen transfer rates were investigated systematically in the CellCul-20A bioreactor with the device of cage aeration in this paper. The temperature, rotating speed, aeration rate and foam breaker, which affected the rate of oxygen transfer were studied, respectively. The mass transfer rate increased significantly with the aeration while the foam breaker had a negative effect on kLa, especially in a cell culture medium with 5% (v/v) calf serum. The oxygen transfer coefficients of surface and deep aerations were correlated, based on the experimental data.