The　evolution　of　microstructure　and　texture,　and　their　effects　on　the　microhardness　of　high　purity　oxygen　free　copper　tube　during　deformation　were　investigated　by　electron　backscattered　diffraction　technology　and　hardness　testing.　The　results　reveal　that　for　low　strains,　the　microstructure　is　elongated　along　the　axial　direction,　and　the　average　grain　size　is　decreased　while　the　low　angle　grain　boundaries　are　increased　as　strain　increase,　and　thus　the　microhardness　value　is　increased　significantly.　After　deformation,　there　exists　a　major　＜111＞　fiber　texture　with　a　secondary　＜001＞　one　paralleling　to　the　axial　direction.　For　high　strains　above　77%,　both　the　grain　size　and　low　angle　grain　boundary　are　decreased　slightly,　and　the　microhardness　is　increased　to　some　extent　as　the　strain　increase.　The　co-action　of　working　hardening　and　the　deformation　result　in　the　increase　of　＜001＞　texture　and　＜111＞,　which　is　great　different　from　the　conventional　cases.　The　initial　deformation　is　suggested　to　favor　detwinining,　while　further　deformation　induces　reappearing　of　twins.　©　2019,　Journal　Office　of　Special　Casting　and　Nonferrous　Alloys.　All　right　reserved.