Abstract: Uranium nitride nuclear fuel has lots of advantages, such as high uranium density, high melt point, high thermal conductivity, low thermal expansion coefficient and high irradiation stability, so it is an important candidate fuel for the future nuclear energy systems including space nuclear reactor, nuclear rocket, fast reactor and ADS. In this research, U₂N₃ powders were fabricated by nitriding reaction of nitrogen and uranium powders. UN ceramic pellets with density of 93.5%TD (theory density) have a little residual metal uranium when U₂N₃ powders with median particle size of 38.3 μm were hot press sintered in vacuum at 1 600 ℃. But UN ceramic pellets can be vacuum hot press sintered to 96.1% TD at 1 550 ℃ by 18.1 μm U₂N₃ powders, without residual uranium, in which the total mass content of U and N is 99.57%, the impurity content of each heavy metal is less than 50 μg/g, the oxygen content is 1 048 μg/g, and the carbon content is 502 μg/g. U₂N₃ will completely be decomposed into UN above 1027 ℃, and UN will also be decomposed above 1 627 ℃。