The multi-stage fluidized bed (MSFB) reactor with several stages connected in series prevents gas and solids back-mixing effectively and obtains the plug-flow reactor performance. Besides, different process steps can be accomplished in a single reactor by establishing different temperatures and/or concentrations in each stage. Therefore, multi-stage fluidized bed reactors are acknowledged as novel and flexible multi-phase flow reactors for heterogeneous catalytic processes, especially with the intermediates as the desired products. Typical process developments in the industry involve the methanol to aromatics (MTA), regeneration in fluid catalytic cracking (FCC), and hydrogenation of nitrobenzene to aniline. The purpose of this article is to provide a comprehensive review of the fundamental research as well as particular industrial applications on multi-stage fluidized bed reactors in the Fluidization Laboratory of Tsinghua University (FLOTU).