Normal　carbon　source　black　carbon　was　substituted　by　graphene　which　was　dispersed　in　N-Methyl-2-pyrrolidone　and　nanocrystalline　WC-Co　composite　powders　were　prepared　using　a　short　process　in-situ　reduction　and　carbonization　reaction　method.　The　results　show　that　graphene　as　the　carbon　source　could　decrease　the　reaction　temperature,　and　the　particles　of　WC-Co　composite　powders　are　fine　and　the　particle　size　distributes　uniformly.　Composite　powders　were　consolidated　through　the　spark　plasma　sintering　system　and　the　mean　grain　size　of　WC　in　WC-Co　cemented　carbides　is　about　290　nm.　Vickers　hardness　and　fracture　toughness　of　the　bulk　is　13.877　+/-　0.131　GPa　and　8.3　+/-　0.1　MPa.m(1/2),　respectively.　HRTEM　images　show　that　the　grain　boundaries　of　interfaces　between　WC/WC,　WC/Co　and　WC/C　are　of　low　misfit.