Microstructure　and　properties　of　the　Fe-20Mn-3Cu-1.38C　TWIP　(twinning　induced　plasticity)　steel　TIG　welding　joint　before　and　after　solution　treatment　have　been　studied　by　uniaxial　tensile　test,　microstructure　observation,　X-ray　diffraction　and　microhardness　test.　The　results　revealed　that　the　microstructure　of　welding　joint　without　solution　treatment　was　composed　by　coarse　columnar　crystals　with　specific　orientation.　Furthermore,　a　large　number　of　granular　carbides　precipitated　in　weld　zone　and　heat　affected　zone.　After　solution　treatment,　the　isometric　crystal　was　obtained　and　the　precipitated　carbide　was　dissolved　completely.　Meanwhile,　the　tensile　strength　of　welding　joint　reduced　from　953MPa　to　870MPa,　while　the　elongation　increased　from　41.85%　to　66.35%.　The　microstructure　and　properties　has　been　improved　obviously　after　solution　treatment.　The　tensile　strength　and　elongation　of　base　material　is　1　100　MPa　and　92.25%　respectively.　Both　kinds　of　tensile　samples　fractured　in　the　heat　affected　zone　and　the　fracture　appearance　showed　typical　ductile　fracture　characteristic.　©　2016,　Editorial　Board　of　Transactions　of　the　China　Welding　Institution,　Magazine　Agency　Welding.　All　right　reserved.