Ultra-coarse　grained　cemented　carbides　are　often　used　under　conditions　of　concurrently　applied　stress　and　high　temperature.　Improvement　of　high-temperature　mechanical　performance　of　ultra-coarse　grained　cemented　carbides　is　highly　desirable　but　still　a　big　challenge.　In　this　study,　it　is　proposed　that　the　high　temperature　compression　strength　of　ultra-coarse　cemented　carbides　can　be　enhanced　by　modulating　hard　matrix　grains　by　activated　TaC　nanoparticles,　through　solid　solution　strengthening　of　Ta　atoms.　Based　on　the　designed　experiments　and　microstructural　characterizations　combined　with　finite　element　simulations,　the　grain　morphology,　stress　distribution　and　dislocation　configuration　were　studied　in　detail　for　ultra-coarse　grained　cemented　carbides.　The　mechanisms　of　Ta　dissolving　in　WC　crystal　and　strengthening　ultra-coarse　grains　through　interaction　with　dislocations　were　disclosed　from　the　atomic　scale.　This　study　opens　a　new　perspective　to　modulate　hard　phases　of　cemented　carbides　for　improving　their　high　temperature　performance,　which　will　be　applicable　to　a　variety　of　cermet　and　ceramic-based　composite　materials.　(c)　2022　Published　by　Elsevier　Ltd　on　behalf　of　The　editorial　office　of　Journal　of　Materials　Science　&　Technology.