Fe-20Mn-3.0Cu-1.38C　alloy　steel　with　high　strength　and　high　ductility　was　prepared　by　vacuum　melting　method.　Influence　of　different　cold-rolled　deformation　(12.8%-73.37%)　on　microstructure　and　tensile　properties　of　Fe-20Mn-3.0Cu-1.38C　steel　were　investigated　by　unidirectional　tensile,　X-ray　diffraction,　OM　and　TEM,　and　the　deformation　mechanism　of　32.28%　cold　rolled　alloy　steel　was　studied.　The　results　show　that　the　Fe-20Mn-3.0Cu-1.38C　steel　before　and　after　deformation　is　fully　composed　of　austenite　without　martensite.　The　yield　and　tensile　strength　increase　apparently　with　cold　rolled　deformation　increasing,　while　the　elongation　is　opposite.　When　the　cold　rolling　deformation　is　32.28%,　the　alloy　steel　exhibits　superior　tensile　properties,　the　yield　strength　and　tensile　strength　are　1383.99　MPa,　1619.83　MPa,　respectively.　And　it　still　retains　41.12%　elongation.　During　its　tensile　deformation　with　32.28%　cold　rolling　deformation,　TWIP　effect　is　happened,　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.　©,　2015,　Chinese　Mechanical　Engineering　Society　of　Heat　Treatment.　All　right　reserved.