An axial mixing of liquid down stream flow in mobile beds is studied on the basis of the dispersion model. The axial dispersion coefficient of liquid is evaluated by a pulse response method experimentally. The values increase with the gas and liquid velocities, the packing density, the diameter of the column and the liquid viscosity increased, and decreased when the diameter and the packed height of the packings increased. It is also found that the liquid dispersion coefficients closely connected with the packings dispersion coefficient. The values of the liquid Peclet number are correlated to the particle Peclet number.