Abstract: For hightemperature gascooled reactor, microspheric UO₂ was used as the fuel kernel. Sol-gel process was widely used to fabricate UO₂ kernel. In order to simplify the process flow, and to reduce the waste, gel-casting process was developed to manufactureUO₂ kernel. The chemical reactions were compared and analyzed in sol-gel and gelcasting processes, and the effect on the diameter of UO₂ kernel was studied. The UO₂ kernels with the size of 710 μm, n(O)/n(U)≤2.01, density of 10.70 g/cm³were obtained by gel-casting process followed by heat treatment.