Abstract—: The sintering mechanisms of WC–Al2O3nanopowder compositions with different contents of al-umina particles (1, 3, and 5 wt %) have been studied. The samples of WC–Al2O3ceramics are obtained by electropulse (spark) plasma sintering (SPS) in vacuum by heating to a temperature of 1450°C at a rate of 50°C/min under a uniaxial stress of 70 MPa. Plasma-chemical nanopowders of tungsten monocarbide and submicron powders of alumina are used to fabricate the ceramics. The density, microstructure, phase composition, microhardness (HV), and crack resistance (KIC) of the ceramics have been studied. It has been shown that the use of SPS enables the production of WC-Al2O3ceramics with a high relative density (95.4–98.1%) and a homogeneous microstructure with the ultrafine grain size (0.1–0.2 μm). The X-ray phase analysis has shown that during the SPS of WC–Al2O3ceramics the formation of undesirable W2C phase occurs which results in a decrease in the crack resistance. To reduce the intensity of formation of W2C particles, free carbon in the form of colloidal graphite (0.1, 0.2, and 0.3 wt %) is introduced into the WC–Al2O3ceramic. Using the Young–Cutler model and the model of diffusion resorption of pores it has been shown that the main mechanism behind the SPS of WC–Al2O3ceramics is a grain-boundary diffusion. It has been found that the introduction of graphite leads to a decrease in the activation energy of SPS of the WC–Al2O3ceramics, which is probably due to a reduction in the W2C particle content to 0.5 wt %.