Commerical pure WC powders of 0.2, 0.4, 0.8, 2.0 and 3.0 m in diameter were sintered by spark plasma sintering process at 1300 °C, respectively. By analyzing the XRD patterns of the initial powders and the microstructure of the sintered samples, it is affirmed that the powders with an average size of 0.8 m exhibits the best activity and sintering property. To optimize sintering temperature, the sintering of 0.8 m powders was carried out at 1200-1700 °C. The specimen sintered at 1300 °C has a density of 15.49 g/cm3 and an average grain size of about 0.7 m, and exhibits the most excellent mechanical properties. The corresponding Vickers hardness and transverse rupture strength are 2469 HV and 1656 MPa, respectively.