Abstract: Effects of solution and aging treatment on microstructure and mechanical properties of extruded AM50+xCa alloys(x=0,1,2 wt%) were studied.With solution time increasing,the secondary phase Mg17Al12 was solid solutioned dispersedly into the Mg matrix while Al2Ca was rather stable,partly became thinner ,then gradually broken and spheroidized.With aging time increasing,Mg17Al12 was precipitated from the Mg matrix as the form of particles and Al2Ca changed a little.After solution treatment,the hardness and tensile properties of extruded AM50+xCa alloys decreased.After aging treatment,the alloy hardness increased to its peak fast then decreased,tensile properties of AM50 and AM50+2%Ca decreased a little while tensile properties of AM50+1%Ca increased a little.The ductility of extruded AM50 and AM50+2%Ca increased remarkably after solution treatment and decreased a little after aging treatment,while ductility of extruded AM50+1%Ca decreased a little after solution treatment and increased remarkably after aging treatment.