Abstract: A two-dimensional mixing pool stochastic model is proposed for simulating liquid flow and mass transfer in a packed column, by which the concetra-tion profiles of the liquid and gas phases can be computed. The main features of this model are: (a) any complicated liquid flow pattern can be closely simulated by adjusting the flow and the mixing among mixing pools in both the radial and the axial directions, (b)the stochastic nature of liquid distribution is fully considered in the model computation. Both theoretical and experimental investigations show that the drop of mass transfer efficiency with increasing column diameter or column height is mainly attributed to non-uniform liquid flow, intensified axial mixing, and imperfect radial mixing.