Gas-liquid-liquid three-phase flow in cross microchannels has been widely used in flow chemistry and process intensification. At present, the flow and mass transfer characteristics in this microchannel are not well understood. In this work, the hydrodynamics and liquid-liquid mass transfer characteristics of gas-liquid-liquid three-phase flow were systematically investigated. For the gas-liquid-liquid hydrodynamics, the bubble/droplet size prediction model based on the multiphase cooperative behavior was proposed, which could be used in predicting droplet/bubble size in flow systems. For the gas-liquid-liquid mass transfer process, the semi-empirical prediction formula of the mass transfer coefficient was obtained by considering the vortex strength, the interfacial area and the effective mass transfer area. This work could be the comprehensive study of gas-liquid-liquid three-phase flow and liquid-liquid mass transfer under gas enhancement in the cross microchannel.