VC was added to the raw oxide materials which were synthesized to the nanocrystalline WC-Co composite powder by the in-situ reduction and carbonization process. The nanocrystalline WC-Co alloys were fabricated by the spark plasma sintering technique using the prepared WC-Co composite powder. The phase constitution microstructure characteristics and mechanical properties of the sintered cemented carbides were analyzed. The study proposed that VC plays a significant role in decrease the grain size of the prepared WC-Co alloy. The nanocrystalline WC-Co alloy with high hardness and good fracture toughness properties can be obtained as the amount of VC addition is appropriate.