The mass transfer of cyclohexanone oxime (CHO) from n-octane (continuous phase) to H2SO4 (dispersed phase) was enhanced in milliscale packed beds under large phase ratios. The holdups of two phases were determined, and the effects of structure and operating parameters on the overall mass transfer coefficient of the organic phase (K(0)a) were also investigated, including placement mode, surface property, size of particle and bed, flow rate and phase ratio, and CHO concentration. Different flow regimes were found in different placement modes and surface properties. Compared with tubes, packed beds showed 1 order of magnitude increase of K(0)a. A prediction model for K0a was proposed and showed good agreement with the experimental results. Pressure drop and energy dissipation were further measured to access the mixing efficiency. These results are therefore expected to contribute to the novel process of the caprolactam industry and expand the applications of microflow technology.