This work aims at compiling the important works on the modeling of a fluid catalytic cracking (FCC) riser reactor. The modeling of a riser reactor is very complex due to complex hydrodynamics and unknown multiple reactions, coupled with mass transfer resistance, heat transfer resistance and deactivation kinetics. A complete model of the riser reactor should include all the important physical phenomena and detailed reaction kinetics. As the computational fluid dynamics (CFD) is emerging as a powerful tool for modeling the FCC riser, various works on riser modeling using CFD are also included in the paper.