Using ammonium metatungstate, soluble cobalt salt, soluble carbon as the raw materials, ultrafine WC-Co composite powder was synthesized by spraying conversion, calcination, in-situ reduction and carbonization route. The composite powder fabricated by the similar route, only increased a short-time ball milling process after the calcination, was more disperse. Ultrafine WC-Co cemented carbides were prepared by spark plasma sintering with this two kinds of powders. The morphology, microstructure and mechanical properties of composite powders and cemented carbides were characterized by SEM, XRD, Vickers hardness tester and so on . The results show that the composite powder fabricated via the route without short-time ball milling process is spherical and has obvious sintering characteristics. WC particles are bonded together, the sintering neck and abnormal grain growth can be observed obviously. Powder fabricated via the route with a short-time ball milling process is more disperse. The fcc-Co and hcp-Co were existed in all two kinds of powders, the grain size of WC is 0.26 μm. There are a few pores exists in the alloy prepared by the spherical composited powder. The density is lower and the WC has abnormal growth. The mechanical properties of the alloy prepared by the dispersed composite powder are better.