Metal nitride and/or carbide ceramic powders, TiC, TiN, TiCN, and TaC ceramic powders, were selected as initial materials for simulation experiments of superhigh-pressure extrusion and high-pressure and high-temperature sintering, whose fragmentation law and sintering behavior were evaluated by using SEM, laser particle size analyzer, and XRD. Meanwhile, the compressibility and agglomeration of the powders were calculated and analyzed. Results show that intragranular cracks, fragmentation, and particle breakage take place in the ceramic powder particles, and crushed fine particles adhere to coarse particles and form larger particle aggregates, or filling the particle voids during sintering. The diffraction peaks shift to higher angles with a certain FWHM broadening and decreased peak intensity. The existence of intragranular cracks and honeycomb groove damage has a negative impact on the performance of the sintered body. In addition, the ceramic powders show high compressibility and strong agglomeration under the action of superhigh pressure. (C) 2020 Elsevier B.V. All rights reserved.