In　this　work,　the　corrosion　resistance　of　CD4MCu　(UNS　J93370)　duplex　stainless　steel　both　at　cold-rolled　and　annealed　states　was　studied　with　respect　to　microstructure,　alpha＇-martensite,　alpha/gamma　phase　boundaries,　LAGBs　(low-angle　grain　boundaries),　sigma　3　and　textures.　A　series　of　characterization　methods　including　optical　microscopy,　electron　backscatter　diffraction　(EBSD),　x-ray　diffraction　(XRD)　and　electrochemical　testing　were　applied　to　analyze　the　microstructure　and　interpret　the　corrosion　resistance　changes.　The　results　show　that　as　the　cold　rolling　deformation　increases,　the　phase　spacing　decreases　and　the　gamma/alpha　interphase　boundary　ratio　increases.　Strain-induced　martensite　forms　during　plastic　deformation　and　the　amount　increases　as　the　deformation　goes　on.　After　cold　rolling,　Cu,　S,　brass　and　Goss　textures　form　in　gamma　phase,　and　weaker　alpha-　and　gamma-fiber　textures　form　in　alpha　phase.　After　annealing,　the　texture　intensity　in　the　gamma　phase　is　weakened,　while　the　gamma-fiber　texture　in　the　ferrite　phase　is　enhanced.　The　corrosion　resistance　can　be　improved　by　appropriate　deformation　and　annealing.　The　increment　of　LAGB　and　sigma　3　grain　boundary　with　low　interfacial　energy　and　the　favorable　textures　induced　during　deformation　are　suggested　to　be　responsible　for　the　improvement　in　the　corrosion　resistance.　They　offset　the　negative　effects　of　alpha＇-martensite　and　defects　on　the　corrosion　resistance.　As　a　function　of　deformation　level,　the　corrosion　resistance　of　both　the　deformed　and　annealed　samples　enhanced　first　and　then　decreased,　reaching　the　best　corrosion　resistance　at　60%　deformation.