Abstract: The MOX fuel has been successfully applicated in the LWRs and FBRs. It is very inconvenience to manufacture MOX fuel due to the radioactivity and poison of Pu. Based on the comparability of the thermodynamics and phase diagrams of U-Ce-O system and U-Pu-O system, and the analysis of the manufacturing simulation technology of MOX fuel pellets, it is possible that the U-Ce-O system is used to simulate the U-Pu-O system in the manufacturing test of MOX fuel pellets.