Design: parameters of bipolar plate are greatly influencing the mass transfer in polymer electrolyte membrane fuel cells. Water accumulation in the catalyst layer and gas diffusion layer causes the mass transport limitation, resulting in an inhibition of gaseous reactant transport to the reaction sites. To carve out the mass transport problems, the optimum design of flow channel is essential with profound understanding of water transport phenomena. Here, we investigate the effect of channel-rib width on dynamic behavior of liquid water in a gas diffusion layer using the multiphase lattice Boltzmann method. We simulate the various channel-rib width configurations and compare the simulated results. We present the water saturation profile with temporal variations of water distribution and relative pressure distribution. The results show that the channel-rib width plays an important role on water transport dynamics in a gas diffusion layer as well as water breakthrough and creeping. The influence of channel-rib width becomes significant as it increases.