Three　new　high-strength　and　high-plasticity　Fe-20Mn-XCu-1.3C　steels　with　different　copper　content　were　prepared　by　vacuum　melting.　The　effects　of　copper　content　on　the　microstructures　of　such　steels　and　deformed　ones　were　observed　by　OM,　and　effects　on　mechanical　properties　were　investigated　by　unidirectional　tensile.　The　experimental　results　indicate　that　the　undeformed　and　deformed　microstructures　of　Fe-20Mn-XCu-1.3C　steels　are　single　austenitic　phase.　The　yield　strength　and　elongation　increases　with　the　increasing　of　copper　content,　while　the　tensile　strength　decreases　with　it.　Fe-20Mn-3.0Cu-1.3C　has　a　comprehensive　property　which　the　tensile　strength　is　1256MPa,　the　elongation　percentage　is　77.6%　and　the　strength-plasticity　product　achieves　97465.6MPa　·%.　As　the　increasing　copper　content,　the　stacking　fault　energy　value　of　these　steels　was　found　to　be　increased,　so　the　formation　of　deformation　twin　were　delayed　and　its　volume　fraction　increasing　rate　was　also　decreased　during　tensile　deformation,　but　the　dislocation　glide　were　strongly　activated.　Fe-20Mn-XCu-1.3C　steels　had　high　work　hardening　rate,　and　the　hardening　rate　decreased　with　the　increasing　of　copper　content.