The　friction　process　of　the　WC–Co　cemented　carbides　in　the　different　conditions　was　investigated　by　molecular　dynamics　simulation　in　this　work.　The　effects　of　grain　size,　friction　load,　and　sliding　velocity　on　the　friction　and　wear　behavior　of　the　cemented　carbides　were　analyzed.　The　friction　and　wear　microscopic　mechanism　of　the　cemented　carbides　in　the　atomic　scale　was　revealed.　The　results　show　that,　with　the　increase　of　grain　size,　the　dislocation　slip　in　the　Co　and　WC　phases　gradually　plays　more　important　role　in　the　friction-induced　plastic　deformation　mechanism　rather　than　the　grain　rotation.　The　increase　of　friction　load　may　lead　to　the　deformable　Co　bonding　phase　being　extruded　from　the　surface　and　removed　first.　Nonetheless,　the　extrusion-wear　mechanism　of　the　Co　phase　can　be　suppressed　by　reducing　the　WC　grain　size,　and　the　sliding　wear　resistance　of　the　cemented　carbides　can　be　improved.　Besides,　the　increase　of　sliding　rate　may　reduce　the　wear　rate.　The　main　reason　is　that,　in　the　process　of　high-speed　sliding,　the　nucleation　and　expansion　of　dislocation　in　each　phase　of　the　subsurface　layer　lacks　the　continuous　driving　stress,　and　the　dislocation　density　is　low.　Therefore,　WC　is　difficult　to　fracture,　and　the　wear　degree　caused　by　Co　phase　being　extruded　from　the　surface　is　significantly　reduced.　©　2022　Beijing　Research　Institute　of　Powder　Metallurgy.　All　rights　reserved.