By　using　the　atomic　cluster　model,　face　centered　cubic　(FCC)　Co81.8Si9.1B9.1　compound　is　designed　and　synthesized　as　ductile　single-phase　ribbons　successfully.　These　ribbons　show　strong　orientation　along　(111)　and　high　magnetocrystalline　anisotropy　with　a　coercivity　of　430Oe　and　squareness　of　0.82　at　room　temperature.　The　large　spin-orbit　coupling　also　contributes　to　the　delocalization　of　Co　3d　band　and　increased　character　of　itinerant　electrons　which　account　for　the　structural　stability　and　magnetic　behaviors.　The　experimental　electronic　structure　indicates　that　the　magnetic　performance　can　be　improved　further.　This　work　not　only　develops　a　low-cost　Co-based　material　for　hard　magnetic　applications,　but　also　extends　the　atomic　cluster　model　into　the　design　of　new　crystalline　materials.