In　this　paper,　the　effects　of　residual　stress　(RS)　on　the　microstructure,　crystal　defects　evolution,　and　mechanical　behavior　of　WC-Co　cemented　carbides　were　investigated　by　molecular　dynamics　(MD)　simulations.　The　microscopic　behaviors,　such　as　dislocation　generation,　proliferation　and　interaction,　microcrack　initiation　and　propagation,　were　studied　for　the　WC-Co　cemented　carbides　under　different　predefined　stress　states.　The　results　showed　that　the　cemented　carbide　with　RS　had　a　lower　compressive　strength.　The　dislocation　densities　in　both　WC　and　Co　increased　significantly　compared　with　those　in　the　cemented　carbide　without　RS,　and　the　dislocations　in　WC　with　RS　initiated　at　a　smaller　strain.　Due　to　the　presence　of　RS,　the　critical　stress　required　for　microcrack　nucleation　at　WC/WC　grain　boundaries　and　WC/Co　phase　boundaries　decreased,　and　the　proportion　of　crack　propagation　along　WC/WC　grain　boundaries　increased.　The　RS　increased　the　probability　of　fracture　in　Co　and　decreased　the　probability　of　WC　transgranular　fracture.　It　was　proposed　that　tailoring　microstructure　to　decrease　the　WC　contiguity　would　be　beneficial　to　improve　the　compressive　strength　of　WC-Co　cemented　carbides　with　inevitable　RS.