Compared　to　duplex　stainless　steels　(DSSs)　prepared　by　traditional　methods,　specimens　produced　through　laser　powder　bed　fusion　(LPBF)　exhibit　excellent　yield　strength　but　lower　elongation.　To　improve　elongation,　understanding　microstructure　evolution　during　uniaxial　tensile　testing　is　crucial.　This　study　investigates　the　slip　behavior,　grain　boundary　evolution,　and　phase　transformation　of　LPBF　2205　duplex　stainless　steel　during　tensile　deformation　using　in-situ　electron　backscatter　diffraction　(EBSD).　Results　show　the　formation　of　slip　bands,　which　increase　in　number　as　loading　stress　rises.　The　primary　slip　systems　activated　are　{110}　in　ferrite　and　{111}　in　austenite.　In　the　ferrite　phase,　slip　dislocations　accumulate　and　generate　low-angle　grain　boundaries　(LAGBs),　which　evolve　into　high-angle　grain　boundaries　(HAGBs),　refining　the　grain　structure.　Numerous　Σ3　annealing　twins　form　in　the　austenite　phase,　but　detwinning　and　twinning　reduce　Σ3　content　as　deformation　processes.　Ferrite　and　austenite　exhibit　good　stability　during　the　initial　stages　of　tensile　deformation.　However,　some　austenite　transforms　into　martensite　through　the　transformation-induced　plasticity　(TRIP)　effect　at　the　final　stages　of　deformation,　which　helps　relieve　stress　concentration　and　delays　material　fracture.　This　study　provides　valuable　insights　for　optimizing　microstructure　to　improve　the　mechanical　properties　of　LPBF　materials.　©　2024　The　Authors