The　microstructure　evolution　and　changes　in　the　structures　of　crystal　defects　of　the　nanocrystalline　WC-Co　composite　in　the　process　of　uniaxial　compression　were　studied　by　simulations　at　both　room　and　high　temperatures.　The　deformation　processes　were　demonstrated　as　a　function　of　stress　and　temperature　for　the　stages　prior　to　and　after　yielding　of　the　composite.　The　Peierls　stresses　were　evaluated　for　Co　and　WC　dislocations　with　increasing　temperature.　The　deformation　mechanisms　for　each　stage　of　the　stress-strain　curve　were　disclosed,　in　which　the　effect　of　temperature　was　clarified.　It　was　found　that　with　the　increase　of　stress,　from　elastic　deformation　to　plastic　deformation　then　to　yielding　of　the　composite,　the　dominant　mechanisms　are　grain　boundary　migration,　formation　and　motion　of　dislocations　in　Co,　concurrent　motion　and　reaction　of　dislocations　in　Co　and　WC,　and　then　rotation　of　WC　grains　in　combination　with　motion　of　Co　and　WC　dislocations.　At　the　yielding　stage,　sliding　of　WC　grain　boundaries　plays　an　increasingly　important　role　in　the　contribution　to　plastic　deformation　at　high　temperatures.　With　strain　the　proportion　of　mobile　dislocations　decreases,　and　dislocations　pile　up　at　triple　junctions　of　WC　grains,　WC/WC　grain　boundaries　and　WC/Co　phase　boundaries　in　priority　order,　leading　to　the　nucleation　and　propagation　of　microcracks　in　these　regions.