Traditional　low-alloyed　Mg-Al-Ca-Mn　extrusion　alloys　always　show　a　low　strength　and　a　high　tension　compression　yield　asymmetry.　In　the　present　work,　Mg-1Al-1Ca-0.2Mn　(AXM1102,　wt.%)　alloys　were　extruded　at　150-350　degrees　C　to　produce　different　grain　structure　and　mechanical　properties.　It　is　shown　that　AXM1102-150　(extruded　at　150　degrees　C)　sample　exhibits　superhigh　strength　in　both　tension　and　compression,　which　exhibited　a　yield　strength　(YS)　of　428　MPa　in　tension　and　416　MPa　in　compression.　Namely,　ultrahigh　strength　and　low　tension-compression　yield　asymmetry　were　both　obtained.　The　ultrahigh　strength　was　found　to　be　ascribed　to　the　ultra-fine　dynamically　recrystallized　(DRXed)　grains　(0.47　mu　m)　together　with　grain　boundary　co　segregation　of　Ca　and　Al　atoms.　Submicron　DRXed　grains　accounts　for　the　improved　tension-compression　yield　asymmetry　through　suppressing　{10-12}　twining　during　compression.　Additionally,　the　discontinuous　yielding　was　detected　during　tension　of　AXM1102-150　alloy,　which　is　potentially　related　with　the　high　energy　barrier　required　for　dislocation　emission　caused　by　grain　boundary　co-segregation　of　Al　and　Ca　atoms.　Once　the　tensile　stress　reaches　the　peak　value,　the　mobile　dislocation　density　increases　immediately,　thus　the　tensile　stress-strain　behavior　of　the　AXM1102-150　alloy　is　dominated　by　strain　softening.　The　results　indicate　that　low-alloyed　Mg-Al-Ca-Mn　alloys　demonstrate　tremendous　potential　as　next　generation　ultrahigh-strength　and　low　tension-compression　yield　asymmetry　wrought　Mg　alloys.