In　this　study,　we　investigated　the　microstructures　and　mechanical　properties　of　Mg-6Gd-1Er-0.5Zr　(GE61K)　sheets.　The　results　show　that　the　rolling　temperature　has　a　remarkable　influence　on　microstructures,　age-hardening　responses　and　mechanical　properties　of　GE61K　sheets.　The　microstructures　varies　with　the　increase　in　rolling　temperatures,　i.e.　microstructures　were　dominated　by　the　mixture　of　dynamic　re-crystallized　(DRXed)　grains　and　un-DRXed　grains　at　300　degrees　C,　by　DRXed　grains　at　350　degrees　C,　and　by　un-DRXed　grains　at　400　degrees　C　and　450　degrees　C.　Rolling　at　300　degrees　C　leads　to　a　formation　of　the　bimodal　microstructure　which　contains　equilibrium　Mg-5(Gd,　Er)　precipitates　and　a　large　number　of　dislocations.　These　dislocations　leads　to　a　formation　of　novel　chain-like　precipitates　which　comprise　dominant　beta＇,　beta＇(F)　(or　beta＇(T)),　tail-like　＂hexagonal　ring＂　layers,　individual　＂zig-zag＂　chain　and　individual　＂hexagonal　ring＂,　eventually　improving　age-hardening　responses.　The　chain-like　precipitates　are　beneficial　for　achieving　a　good　strength-ductility　balance　by　dividing　the　matrix　into　nano-scale　units　and　forming　subsequent　honeycomb　structures.　As　a　result,　the　R-300　degrees　C　sheet　shows　good　mechanical　properties,　i.e.　ultimate　tensile　strength　(UTS)　of　367　+/-　3　MPa,　yield　strength　(YS)　of　349　+/-　4　MPa　and　elongation　(EL)　of　9.1　+/-　1.5%,　respectively.　However,　such　strength-ductility　balance　is　destroyed　sharply　as　soon　as　the　rolling　temperature　increases　to　400　degrees　C　because　of　the　microstructure　variations.　(C)　2021　Elsevier　B.V.　All　rights　reserved.