A multi-tube air-lift loop reactor (MT-ALR) is presented in this paper.Based on the energy conservation, a mathematical model describing the liquidcirculation flow rate was developed, which was determined by gas velocity, the crossareas of riser and downcomer, gas hold-up and the local frictional losscoefficient.The experimental data indicate that either increase of gas flow rate orreduction of the downcomer diameter contributes to higher liquidcirculation rate.Thecorrelation between total and the local frictional loss coefficients was also established.Effects of gas flowrate in two risers and diameter of downcomer on the liquidcirculation rate were examined. The value of total frictional loss coefficient wasmeasured as a function of the cross area of downcomerand independent of the gas flow rate.The calculated results of liquidcirculation rates agreed well with the experimental data with an average relative error of9.6%.