The risers of a conventional fluidized bed reactor and a stage fluidized bed reactor for the convention of methanol to olefins (MTO) were simulated using computational fluid dynamics. The reaction rates of the MTO reaction were validated to successfully match with the literature experiment. Then, the reactor stage parameters were examined by using the 2k design of the experiment method, including the number of reactor stages, the thickness of the reactor stage, and the wall temperature of the reactor stage. The stage circulating fluidized bed riser decreased the yield of ethene but increased the yield of propene and light olefins. From the obtained solid volume fraction profile, the stage circulating fluidized bed riser could reduce the back-mixing and increase the system turbulence, which promotes the light olefins of the MTO reaction yield. The wall temperature of the reactor stage did not significantly affect the chemical reaction in the circulating fluidized bed riser.