The　evolution　of　microstructure　and　grain　orientation　of　CoCrFeMnNi　high　entropy　alloy　during　tensile　deformation　were　investigated　using　electron　backscatter　diffraction　technology.　The　results　show　that　the　original　microstructure　exhibits　equiaxed　grain　morphology　and　possesses　annealing　twinning　in　the　equiaxed　grain　interior,　while　the　tensile　deformation　makes　equiaxed　grains　be　elongated　and　results　in　quick　formation　of　low　angle　grain　boundaries　mainly　distributed　around　the　twinning　boundaries　and　high　angle　grain　boundaries.　During　tensile　deformation　at　room　temperature　which　is　coordinated　through　dislocation　glide,　the　grain　orientation　rotations　are　inhomogeneous,　but　the　matrix　and　twinning　within　individual　grain　rotate　along　approximately　similar　tendency.　For　matrices,　the　tensile　axes　close　to　＜112＞　and　＜111＞　rotate　toward　＜111＞　following　Taylor　model;　the　tensile　axes　close　to　＜101＞　and　close　to　middle　in　the　stereographic　triangle　rotate　to　the　line　of　＜001＞-＜111＞　following　Sachs　model;　the　tensile　axes　close　to　＜001＞　rotate　without　any　significant　regularities.　©　2016,　Editorial　Board　of　Journal　of　Plasticity　Engineering.　All　right　reserved.