The　effect　of　Zn　addition　on　microstructure　and　mechanical　properties　of　the　Mg-2Er　alloy　was　investigated　by　X-ray　diffraction　(XRD)　and　scanning　electron　microscope　(SEM).　The　results　show　that　the　alloys　with　1%　and　2%　Zn　(mass　fraction)　are　composed　of　the　W-phase　and　the　alpha-Mg　matrix.　Meanwhile,　the　addition　of　4%-10%　Zn　results　in　the　formation　of　the　I-phase,　the　W-phase　and　the　alpha-Mg　matrix.　When　the　addition　of　Zn　reaches　12%,　the　W-phase　disappears　and　the　phase　constituents　of　the　alloys　mainly　include　the　I-phase　and　the　Mg4Zn7　phase　besides　the　a-Mg　solid　solution.　The　alloy　containing　6%　Zn　has　better　mechanical　properties,　of　which　the　ultimate　tensile　strength　(UTS)　and　the　yield　tensile　strength　(YTS)　are　about　224　MPa　and　134　MPa,　respectively,　companying　an　elongation　of　10.4%.