The　ingots　of　three　grades　TWIP　steels　with　the　different　carbon　contents,　i.e.　Fe-20Mn-3.0Cu-0.23C,　Fe-20Mn-3.0Cu-0.83C　and　Fe-20Mn-3.0Cu-1.41C　in　mass　percent　(the　0.23C,　0.83C　and　1.41C　TWIP　steel,　respectively),　were　prepared　by　vacuum　induction　melting.　The　effect　of　carbon　content　on　the　microstructures　and　tensile　properties　of　Fe-20Mn-3.0Cu-XC　steels　were　investigated　by　X-ray　diffraction,　OM　and　TEM,　and　the　deformation　mechanism　of　steels　was　studied.　The　results　show　that　the　Fe-20Mn-3.0Cu-XC　steels　prior　to　and　after　deformation　are　fully　composed　of　austenite　without　martensite.　All　of　yield　strength,　tensile　strength　and　the　elongation　at　fracture　are　apparently　increasing　with　carbon　content.　Fe-20Mn-3.0Cu-1.41C　steel　exhibits　superior　tensile　properties.　the　yield　strength　and　tensile　strength　are　501.62MPa　and　1178.4MPa,　respectively.　The　Fe-20Mn-3.0Cu-XC　steels　have　excellent　strain　hardening　ability,　the　maximal　strain　hardening　exponent　can　reach　up　to　0.782　with　the　carbon　content　increases　to　1.41%.　During　the　tensile　deformation　of　Fe-20Mn-3.0Cu-XC　steels,　TWIP　effect　is　the　dominant　deformation　mechanism,　and　the　increase　of　strength　and　plasticity　is　attributable　to　large　quantity　of　dislocation　pile-up,　the　generation　of　deformation　twins　and　the　interaction　of　each　other.