Abstract: A correlation of liquid circulation rate in a multi-tube air-lift loop reactor(MALR) was established on the basis of the momentum balance, in which a new method for the determination of the overall frictional-loss coefficient in air-water system was developed. The method for determining the exposure time of liquid particle in the gas-liquid interphase was proposed, which formed the basis for the calculation of volumetric mass transfer coefficient of gas component according to Higbies penetration theory. The validity of these two correlations was demonstrated by the fairly good agreements between the calculated liquid rate and mass transfer coefficients with the experimental data.