Effects　of　trace　Er　addition　on　the　mechanical　properties,　microstructure,　age-hardening　characteristics　and　recrystallization　behavior　of　the　high　strength　Al-6Zn-2Mg　alloy　have　been　investigated　by　tensile　property　measurement,　optical　microscope　(OM),　X-ray　diffraction　analysis　(XRD),　scanning　electron　microscope　(SEM),　transmission　electron　microscope　(TEM)　and　energy　spectrum　analysis　(EDS).　The　results　show　that　Er　can　greatly　refine　the　grain　size　of　the　alloy,　which　is　attributed　to　primary　Al3Er　as　heterogeneous　substrate　to　sharply　improve　nuclei　rate.　Tensile　strength　of　the　alloy　has　been　significantly　improved　with　Er　addition　as　a　result　of　fine　grain　strengthening　and　precipitated　strengthening.　Meanwhile,　Er　addition　can　improve　age-hardening　effects　by　accelerating　ageing　process　of　the　alloy.　In　addition,　Er　can　inhibit　the　recrystallization　of　the　alloy　and　raise　the　recrystallized　temperature,　resulting　from　the　pinning　effects　of　the　secondary　fine　Al3Er　phase　on　dislocation　and　sub-boundary.