In　this　study,CoCrFeMnNi　high-entropy　alloys(HEAs)with　a　surface　gradient　nanostructure　were　pro-duced　using　industrial　shot　blasting,which　improved　their　mechanical　properties　compared　to　the　untreated　alloy.The　severely　plastically　deformed(SPD)surface　layer　had　a　multi-scale　hierarchical　structure　with　a　high　density　of　stacking　faults,deformation　nanotwins,and　amorphous　domains.The　depth　of　the　SPD　layer　steadily　increased　as　the　shot-blasting　time　increased.The　differences　in　the　microhardness　and　tensile　strength　before　and　after　shot-blasting　demonstrated　the　significant　effect　of　the　SPD　layer　on　the　mechanical　performance.The　microhardness　of　the　homogenized　HEA　was～5　GPa.In　comparison,the　maximum　microhardness　of　the　specimens　after　20　min　of　shot　blasting　was～8.0　GPa　at　the　surface.The　yield　strength　also　improved　by　178％,and　a　large　ductility　of～36％was　retained.Additional　nanograin　boundary,stacking　fault,and　twin　strengthening　within　the　gradient-nanostructured　surface　layer　caused　the　strength　to　increase.During　tensile　deformation,strain　concentration　began　at　the　surface　of　the　specimen　and　gradually　spread　to　the　interior.Thus,the　gradient-nanostructured　surface　layer　with　improved　strain　hardening　can　prevent　early　necking　and　ensure　steady　plastic　deformation　so　that　high　toughness　is　achieved.