In　this　study,　toughening　of　WC-Co　composite　prepared　by　amorphous-crystallization　method　was　investigated.　Co-rich　nanoparticles,　a　Co(W,C)　solid　solution,　were　incorporated　into　the　WC　matrix　through　the　process　integrating　crystallization　of　amorphous　Co2W4C　powder　and　its　in-situ　reaction　with　carbon.　The　microstructural　evolution　of　the　ceramic-metal　composite　during　fabrication　was　studied　in　detail.　Owing　to　the　interactions　between　Co-rich　nanoparticles　coherent　with　the　WC　matrix　and　the　dislocations　and　stacking　faults　inside　WC　grains,　the　composite　exhibited　high　hardness　and　strength　combined　with　exceptional　fracture　toughness.　The　mechanisms　for　the　synergistic　improvement　of　mechanical　properties　of　the　composite　were　disclosed.　[GRAPHICS]