Abstract: Micromixing in the rotating packed bed(RPB) is extensively used and is a novel reactor for fast reactions such as reactive precipitation to synthesize nanoparticles. The study on micromixing in RPB is crucial in understanding the mixing-diffusion mechanism and the behavior of tiny liquid elements in the packing of RPB,which are the theoretical basis for synthesizing nanoparticles by precipitation in RPB.In this paper, on the basis of prior studies,a model describing the turbulent micromixing phenomena and reaction process in RPB is presented in accordance with the flow pattern in RPB. By sufficiently taking into account the unique characteristics of tiny liquid elements in RPB, the concentration distribution outside the packing is simulated by modifying the method proposed by the authors.The computational X_s values with the model are in reasonable agreement with the experimental results.