The　results　suggested　that　the　repeated　plastic　deformation　(RPW)　process　prior　to　hot　extrusion　has　a　great　effect　on　improving　ageing　response　of　the　as-extruded　Mg-6Zn-1Er　alloy.　The　rod-like　beta＇(1),　phase　was　promoted　to　precipitate　abundantly　during　isothermal　ageing　treatment,　which　mostly　contributed　to　the　highest　peak　hardness　of　98.6　(+/-　2.0)HV　in　the　alloy　treated　by　300　repeated　plastic　working　circles.　Furthermore,　the　peak-aged　alloy　displayed　the　highest　tensile　strength,　and　the　values　of　the　ultimate　tensile　strength　and　yield　tensile　strength　were　about　360　MPa　and　252　MPa,　respectively.　(c)　2012　Elsevier　B.V.　All　rights　reserved.