Metastable　high　entropy　alloys　possesses　excellent　ductility　and　toughness,　but　its　low　strength　hinders　its　engineering　applications.　Therefore,　many　studies　have　been　carried　out　to　improve　the　strength　of　metastable　high　entropy　alloys　while　maintaining　high　ductility.　In　this　paper,　a　new　high　entropy　alloy　is　fabricated　by　selective　laser　melting　(SLM)　with　the　addition　of　Si　powder　into　Fe50Mn30Co10Cr10　metastable　high　entropy　alloy　powders,　with　compositions　(Fe50Mn30Co10Cr10)(100-x)Si-x　(x　=　0,　1,　3,　5).　The　results　show　that　the　yield　strength　and　ultimate　tensile　strength　of　Si-containing　metastable　high-entropy　alloys　gradually　increase　with　the　increase　of　Si　elements,　and　the　performance　is　far　better　than　that　of　without　Si　addition.　The　Si　element　increases　the　metastability　of　the　gamma(FCC)　phase　in　the　high-entropy　alloy,　and　promotes　the　phase　transformation　induced　plasticity　by　adjusting　the　twinning　strain　during　the　deformation　process;　so　that　the　total　elongation　of　the　material　prepared　by　SLM　can　reach　30%　and　above.　The　combined　effect　of　multiple　strengthening　mechanisms　such　as　dislocation,　deformation　twinning,　and　phase　transformation　has　greatly　increased　the　strength　of　high-entropy　alloys.　In　addition,　the　excellent　strength-ductility　combination　of　the　alloy　containing　Si　element　indicates　that　the　composition　has　good　printability　for　laser　additive　manufacturing,　which　can　provide　a　reference　for　expanding　the　diversification　of　high-entropy　alloys　in　the　additive　manufacturing　process.