Effects of Al addition to a Mg-Sn-Ca ternary alloy on its microstructure and tensile properties after extrusion were studied via extrusion of Mg-1.0Sn-0.5Ca-xAl (x =0,0.8,2.4 wt％) sheets and analysis of the extruded materials.The results showed that Al addition not only refined the grain size (from 9.8 ± 0.7 μm to 8.3 ± 0.4 μm and 7.6 ± 0.5 μm) but also accelerated the generation of more second phase (from 0.98 to 1.72 and 4.32％).Except for the CaMgSn and Mg2Ca in Mg-1.0Sn-0.5Ca alloy,new phase (Mg,Al)2Ca appeared after Al addition.The addition of Al into Mg Sn Ca alloy induced the textural variation from an initially ED-split double-peaked texture to a weakened texture,i.e.,divergent elliptical texture,due to the effect of particle stimulated nucleation.This eventually contributed to the improvement of mechanical anisotropy as well as the higher Hc value and n-value.For the strain hardening behavior when tension along the TD,the prolonged stage Ⅱ of Al-modified alloys was closely connected with the additional TD textural components,accelerating the activation of more basal slip.The decreased θⅢ0 in stage Ⅲ of Al-modified alloys is beneficial to the grain refinement and the emergence of more second phase.