Non-uniform flow distribution usually exists in a vertical radial flow adsorber, which significantly decreases the utilization of adsorbents. We adopted numerical simulation methods based on the ANSYS Fluent 15.0 software to study the flow pattern in vertical radial flow adsorber, where programs of user-defined functions (UDF) were set up to interpret component equation, momentum equation and energy equation. To solve the problem of non-uniform air distribution, the relationship between the radial pressure drop across the bed and the ratio of cross-sectional area of the central pipe to that of the annular channel was studied, and optimization design of the distributor inserted in the central channel was given by parametric method at the same time. Through comparative analysis in the given experimental condition, the uniformity reached about 99.1% and the breakthrough time extended from 564 s to 1,175 s under the present optimized design method.