Rotating packed beds (RPBs) have attracted widespread attention due to their high mass transfer efficiency. In this paper, gas flow characteristics in a rotating spherical packing bed (RSPB) were investigated by computational fluid dynamics (CFD) and the effects of various parameters were analyzed. The numerical results of velocity distribution and turbulent kinetic energy were in agreement with the published experimental data. The turbulent kinetic energy in the inner edge of the rotor was obviously higher than that in the main region, and a gas end-effect zone was specified when Re-omega/Re-G > 980.4. Reducing the gas flow rate and particle size and increasing the rotational speed decreased the gas backmixing. These results could provide a theoretical basis for the application of RSPBs and the choice of catalyst particle size in the field of gas-solid catalytic reactions.