The　new　Fe-15Ni-12Mn-3.5C-2.5Si　alloy　cast　irons　with　high　strength　and　toughness　were　prepared.　The　alloys　have　an　excellent　capacity　of　plastic　deformation　after　resolution　treatment　with　carbon　atoms　at　high　temperature,　which　was　up　to　50%　continuous　cold　rolling　reduction.　The　results　of　tensile　test　testified　that　the　rolled　sample　after　solution　treatment　at　high　temperature　exhibited　high　tensile　strength　of　730.81　MPa　and　extreme　elongation　of　20%.　The　elongation　has　been　10　times　more　than　that　of　the　same　type　of　QT700-2　ductile　cast　iron　and　it　presented　higher　work-hardening　characteristic　of　plastic　deformation.　The　studies　have　shown　that　the　soluted　matrix　microstructure　is　composed　of　austenitic　and　spherical　graphite　as　well　as　a　small　amount　of　carbide.　Their　high　plasticity　that　resulted　from　TWIP　effect　was　achieved　through　intensive　twin　shear　displacement　on　austenitic　matrix.　Simultaneously,　tensile　strength　of　the　cast　iron　decreased　slightly　and　elongation　improved　greatly　with　the　increase　of　solution　treatment　temperature.　This　kind　of　high　strength　and　toughness　ductile　cast　iron　alloy　would　have　important　application　prospects　for　the　preparation　of　the　engine　crankshaft,　main　shaft　and　other　components　with　the　characteristics　of　vibration,　noise　reduction　and　high　security.