Abstract: Taking into account the chemical reaction rate, internal diffusion and reaction heat, the theoretical model of regeneration process was established to investigate the regeneration within large coked catalyst particle. The results showed that at 650℃, limited by the chemical reaction rate, regeneration process was characterized by the homogeneous model. At temperature over 750℃, internal diffusion of gaseous reactant being the controlling step, the distinct radial profiles of oxygen partial pressure and carbon content were established. The maximum temperature rise in a single spherical catalyst particle increased with the increase of initial regeneration temperature. The maximum temperature rise also increased with the increase of carbon load and CO2/CO mol ratio in product gas. However, the regeneration time needed to reach one burn-off degree was prolonged. The temperature throughout the catalyst particle was homogeneous. The influence of gas flow rate on the regeneration process could be neglected in the case of eliminating external diffusion.