The　Mg-12Gd-1Er-1Zn-0.9Zr　(wt%)　alloy　with　ultra-high　strength　and　ductility　was　developed　via　hot　extrusion　combined　with　pre-deformation　and　two-stage　aging　treatment.　The　age-hardening　behavior　and　microstructure　evolution　were　investigated.　Pre-deformation　introduced　a　large　number　of　dislocations,　resulting　in　strain　hardening　and　higher　precipitation　strengthening　in　the　subsequent　two-stage　aging.　As　a　result,　the　alloy　showed　a　superior　strength-ductility　balance　with　a　yield　strength　of　506　MPa,　an　ultimate　tensile　strength　of　549　MPa　and　an　elongation　of　8.2%　at　room　temperature.　The　finer　and　denser　beta　＇　precipitates　significantly　enhanced　the　strength,　and　the　bimodal　structure,　small　beta-Mg5RE　phase　as　well　as　dense　gamma　＇　precipitates　ensured　the　good　ductility　of　the　alloy.　It　is　suggested　that　the　combination　of　pre-deformation　and　two-stage　aging　treatment　is　an　effective　method　to　further　improve　the　mechanical　properties　of　wrought　Mg　alloys.