The distribution of liquid flow rate is measured in a rectangular bed non-uniformly packed with different particles. The effects of particle properties (size and wettability), liquid properties (viscosity and surface tension) and packed structure on the liquid flow rate distribution are examined. The liquid trickle flow is strongly affected by the capillary force. An experimental equation expressing the liquid flow distribution at the interface between different particles is derived by means of the capillary number. A percolation model combined with the above experimental equation is developed to simulate the liquid flow distribution in the trickle bed. For the trickle flow of liquid droplet, the gravitational and capillary forces are considered to work on the liquid droplet, and the driving force for stochastic liquid flow is assumed to be the potential of the local liquid holdup. Besides a dropping flow in the vertical direction, a permeation flow in the horizontal direction is supposed. The results calculated by the percolation model are in good agreement with the experimental data for various packed systems.