Multiphase reactors are often used as petrochemical, biological and pharmaceutical reactors. Understanding the mixing mechanism responsible for phase mixing is necessary for modeling purposes. Phase mixing may considerably affect reactor performance. In the literature, each phase mixing was often described by the Axial Dispersion Model (ADM), without physical justification. Some authors doubted the validity of the ADM and that it could represent the mixing of the phases and instead proposed other models. Also, some authors studied the fundamental mechanism responsible for phase mixing. For conversion and selectivity prediction purposes, the use of more complex phenomenological phase mixing models is essential when the kinetics are rapid and the interfacial mass transfer is limited. Many literature reviews concerning multiphase reactors have been published. These reviews, however, discuss phase mixing modeling based on the ADM and do not deal with the other phase mixing models. The aim of this work is to review the literature on phase mixing modeling, based on a mechanistic approach, for three kinds of multiphase reactors: the bubble column (solid free), slurry bubble column (small/light particles) and three phase fluidized bed (large/heavy particles) reactors. The common feature of these reactors is the presence of gas bubbles, which considerably influence the phase hydrodynamic. Hence, a mixing model proposed for one of these reactors may be conceptually representative of the mixing of the two others.