CeO2 is an important energy storage material that can be used in solid fuel cells. Adding citric acid can improve the particle distribution of the pyrolytic preparation of CeO2 inside the reactor. Through Fluent, this paper investigated the pyrolysis preparation of CeO2 with the addition of citric acid by adopting the Eulerian multiphase flow model, component transportation model, and standard k-ε turbulence model. The experimental and simulation results suggest that the addition of citric acid can alter the pressure, temperature, and component distributions inside the reactor. When the mass fraction of O2 is 0.3, the concentration distribution effect of the CeO2 component is optimal and its conversation rate is the highest. When the mass fraction of citric acid is 0.04, the concentration distribution effect of the CeO2 component is the best, as witnessed by the high CeO2 concentration at the exit. It was found that an O2 content of 30 wt % and citric acid content of 4 wt % were optimal operating conditions for this technology.