Abstract: The gas flowcharacteristic in an adsorbent bed is a vital problem for furtherstudying the mechanics of gas separation process. In this paper, acomprehensive mathematical model of gas flow and adsorption in anadsorbing bed, which based on mass and momentum conservation law,is established. A typical cyclic process of an axial-flow rapidpressure swing adsorption is numerically studied. The flowpatterns in different cyclic period for pressurization,adsorption, depressurization, desorption and purge, are obtained.The flow characteristics and their difference from the gas flow inan empty bed and a no-adsorption bed are also studied.