Nanocrystalline WC-6Co composite powder that was produced by spray thermal decomposition-continuous and carbonizatio technology was used as raw material, and this paper adopted spark plasma sintering technology to prepare ultrafine cemented carbide. Th microstructure, grain size, porosity, Vickers hardeness, density and Rockwell a hardness (HRA), transverse rupture strength (TRS magnetic saturation induction and magnetic coercivity were studied. The results show that grain of specimen that was prepared by spar plasma sintering technology is 150 nm~300 nm, transverse rupture strength (TRS) is more than 2800 MPa, and Vickers hardness o specimen is more than 19 500 MPa. Ultrafine cemented carbide with high strength and high hardness is obtained.