The　strain　hardening　behavior　of　three　Fe-Ni-Mn-Si-C　TWIP　steels　with　different　carbon　content　were　investigated　by　uniaxial　tensile　tests,　metallography　and　TEM.　The　results　show　that　the　strength　and　elongation　of　TWIP　steels　are　enhanced　with　the　increasing　of　the　carbon　content.　TWIP　steel　has　batter　comprehensive　properties　when　the　carbon　content　is　1.0%,　and　the　strength-plasticity　product　is　83160MPa·%.　The　Hollomon　relationship　is　inapplicable.　At　lower　true　strain　stage,　the　value　of　n　decreases　with　the　higher　carbon　steel,　and　at　higher　true　strain　stage,　the　value　of　n　increases　with　the　increasing　of　the　carbon　content　and　maintains　a　fixed　value.　The　micro　mechanisms　are:　when　the　value　of　strain　is　lower　than　0.12,　dislocation　slipping　is　the　predominant　mode,　deformation　twin　production　is　the　main　mode　when　the　value　of　strain　is　between　0.12　to　0.42.　Deformation　twins　would　be　putted　off　with　the　increasing　of　the　carbon　content,　and　prolonged　stage　II　of　the　strain　hardening　behavior,　enhanced　the　strength　and　ductility　of　the　alloy.