Developing　high　entropy　alloys　that　possess　both　high　strength　and　high　ductility　have　achieved　significant　progress　in　recent　years.　In　this　study,　the　metastable　high　entropy　alloy　Fe50Mn30Co10Cr10　with　Al-Ti　ad-dition　was　formed　by　SLM　technology.　The　effect　of　Al-Ti　addition　on　the　microstructure　and　mechanical　properties　were　investigates.　The　results　shown　that:　with　the　addition　of　Al-Ti　addition　content,　the　grain　size　of　the　alloy　decreases　gradually.　And　also　the　TiAl　intermetallic　compounds　and　nanoscale　L12　phase　are　precipitated　in　the　matrix.　The　phase　transformation　induced　plasticity　(TRIP)　effect　and　twin-induced　plasticity　(TWIP)　effect　can　be　activated　during　the　plastic　deformation　of　the　alloy.　Strength　and　ductility　have　been　well　balanced　because　of　the　combination　of　multiple　mechanisms.　In　the　alloy　with　addition　of　1at.　%　Al　and　1　at.　%　Ti,　the　yield　strength,　tensile　strength　and　elongation　are　543.5　MPa,　854.2　MPa　and　31.8　%　respectively,　which　are　increased　by　110.2　%,　35.5　%　and　70.1　%　compared　with　Fe50Mn30Co10Cr10　alloy　without　Al-Ti　addition.(c)　2023　Elsevier　B.V.　All　rights　reserved.