The present work proposes a method for process intensification of the reaction-separation process. A model of the reactive distillation (RD) system involving a prereactor was developed by use of an equilibrium stage model, and the reaction-separation of a multicomponent mixture was simulated by use of a simulator that was capable of predicting steady-state conditions. The developed model was applied to an RD system with multi-feed, and the reaction-separation and operation performance were examined. As a result, the RD system was found to be usable for reaction-separation interaction phenomena. This process improved the function and performance of conventional reaction-separation process and could be miniaturized.