Rotating packing bed (RPB) has a better mixing performance than traditional mixers and shows potential applica-tion in the petroleum industry. However, acquisition of information about the mixing process directly through experiments is dififcult because of the compact structure and complex multiphase lfow pattern in RPB. To study the mixing character-istic, Fluent, the computational lfuid dynamics (CFD) software, was used to explore the effect of airlfow ifeld on droplet diameter. For conducting calculations, the gas-liquid two-phase lfow inside the packing was simulated with the RNG k-εturbulence model and the Lagrange Discrete Phase Model (DPM), respectively. The numerical calculation results showed that coalescence and breakup of droplets can take place in the gas phase lfow inside the packing and can be strengthened with increased rotating speed, thereby leading to the enlargement of the average diameter.