In　contrast　to　the　conventional　method　that　obtains　a　high　fracture　strength　of　tungsten　carbide-cobalt　(WC-Co)　cemented　carbides　by　reducing　WC　grain　size　to　near-nano　or　nanoscale,　a　new　approach　has　been　developed　to　achieve　ultrahigh　fracture　strength　by　strengthening　the　WC　grains　through　precipitate　reinforcement.　The　cemented　carbides　were　prepared　by　liquid-state　sintering　the　in　situ　synthesized　WC-Co　composite　powders　with　a　little　excess　carbon　and　pre-milled　Cr3C2　particles　having　different　size　scales.　It　was　found　that　the　nanoscale　dispersed　particles　precipitate　in　the　WC　grains,　which　mainly　have　a　coherent　or　semi-coherent　interface　with　the　matrix.　The　pinning　effect　of　the　nanoparticles　on　the　motion　of　dislocations　within　the　WC　grains　was　observed.　The　mechanisms　for　the　precipitation　of　nanoparticles　in　the　WC　grains　were　discussed,　based　on　which　a　new　method　to　enhance　the　resistance　against　the　transgranular　fracture　of　cemented　carbides　was　proposed.