Abstract: The surface modification of the UO₂ powder containing hard particles in the oxygen-containing environment was carried out by roasting modification. The effect of roasting temperature, roasting time and oxygen partial pressure on the ratio of the surface and the oxygen ratio of the UO₂ powder with hard particles was studied by orthogonal test. In this paper, the optimal roasting condition was found by the analysis of extreme difference and main effect diagram. Roasting modified experiment under optimized conditions, the specific surface area of the analysis of the modified calcined UO₂ powder, O/U, apparent density, tap density, powder matrix density, and compare with the original powder properties. Using the traditional way of powder metallurgy powder preparation of modified into pellets, and the same conditions the original powder preparation of pellets can be compared to the green strength, sintering density, microstructure, thermal stability and appearance. The results show that the optimized roasting conditions for roasting temperature is 150 ℃, roasting time of 120 min, roasting oxygen partial pressure was 15%. In this condition, the O/U is 2.14, the collective is 97.7%T.D, the specific surface area of the original powder is increased by 33%, and the strength of the produced billet is increased by 32%. After roasting of sintering block distribution uniform microstructure, thermal stability is good, the average grain size is 12.7 μm. After grinding pellets, the appearance quality is better than the pellets produced by original powder. The cylindrical hole caused by the presence of hard particles is solved effectively.