Mercury porosimeter and scanning electron microscope (SEM) were used to analyze the pore structures evolution and distributions for supercritical CO2 debinding of injection molding ceramics. Classical diffusion equation was used to describe the mass transfer of supercritical CO2 debinding of the injection molded ZrO2 ceramics. The behavior and kinetics of the debinding were studied and analyzed. Results show that the solubility and diffusivity of soluble binder are the key factors in supercritical CO2 debinding, while the diffusivity is a dominant factor. The calculation data from the theoretical model are consistent with the experiment under the condition of enough long debinding time. It is shown that the diffusivity can be obtained by simple theoretical model combined with experimental data. The extraction rate and the extraction kinetics of the process can be predicted using the theoretical model.