The　microstructure　of　Al-6Mg-0.9Mn-0.07Zr-0.2Er　(wt.%),　registered　as　5E61　alloy,　were　investigated　using　optical　microscopy,　scanning　electron　microscopy　and　transmission　electron　microscopy.　The　results　showed　that　the　addition　of　0.2　wt.%　Er　can　refine　the　dendritic　structure　and　form　fine　and　coherent　L12　structured　Al3(ErxZr1-x)　precipitates　in　the　alloy.　After　a　two-stage　homogenization　(280/10h,　460/36h),　the　recrystallization　temperature　of　the　alloy　with　0.2　wt.%　Er　is　about　15　higher　than　that　of　the　alloy　without　Er.　The　better　recrystallization　resistance　may　be　related　to　the　Al3(ErxZr1-x)　precipitates,　which　can　pin　on　dislocations　and　sub-grain　boundaries.　The　hardness　of　the　cold-rolled　alloy　with　0.2　wt.%　Er　is　143HV,　which　is　5%　higher　than　the　alloy　without　Er.　The　exfoliation　corrosion　and　nitric　acid　mass　loss　test　were　also　performed.　The　exfoliation　corrosion　of　the　alloy　is　N　grade,　and　the　mass　loss　is　only　9.84mg/cm2.　©　2017　Trans　Tech　Publications,　Switzerland.