In　this　paper,　the　effect　of　heat　treatment　on　the　microstructure　and　properties　of　a　0.8　mu　m　WC-10%Co　ultrafine　cemented　carbide　was　studied.　The　results　show　that　the　microstructural　differences　in　ultrafine　WC-Co　cemented　carbides　without　and　with　heat　treatment　are　mainly　reflected　in　the　Co　phase.　For　conventional　cemented　carbides,　the　hardness　and　wear　resistance　can　be　increased　only　at　the　expense　of　the　toughness　and　strength.　An　ultrafine-grained　WC-Co　cemented　carbide　with　good　hardness　and　toughness　can　be　obtained　by　strengthening　the　Co　phase　through　an　appropriate　heat　treatment　process,　and　the　service　life　of　the　ultrafine-grained　WC-Co　cemented　carbide　can　be　improved　under　actual　cutting　conditions.