The goal of this study was to determine feasible numbering-up laws to model the gas-liquid distribution in multiple microchannels. Comb-like microchannels were constructed by closely arranging eight capillaries of 0.5-mm inner diameter. The air-water flow in the parallel microchannels was recorded by a high speed CCD camera. After collecting and analyzing a very large number of images, the flow patterns were classified into two zones, zone l and zone II, which were the bubble flow and phase splitting zones, respectively. A model was established to describe the mean sizes and velocities of bubbles and liquid slugs in the two zones at different inlet flow rates of air and water, as well as to distinguish the two-zone operating limits by determining inlet flow rate intervals of the fluids. The calculated results agreed well with the experimental data. Therefore, the model showed a potential application to numbering up comb-like microchannels. (C) 2015 Elsevier Ltd. All rights reserved.