Microstructures of as‐cast and solution‐treated Mg‐xSn (x=2 .18~6 .54) alloys were investiga‐ted .Meanwhile ,the tensile mechanical property ,hardness and impact toughness were tested .The results show that the coarse α‐Mg dendrite among the as‐cast microstructure is refined gradually with increasing the Sn content .Meanwhile ,Mg2Sn phase increases gradually and tends to distribute along grain boundary in the form of continuous network .As‐cast tensile mechanical property and impact toughness at ambient temperature are increased initially ,and then reduced .Tensile strength σb ,elongation δand impact toughness value αnK can reach 151 MPa ,12 .5% and 10 J/cm2 for Mg‐3 .52Sn alloy with the most excellent best prop‐erty ,respectively .At the elevated temperature of 423 K ,σb and δfirst increase to 87 MPa and 19 .0% for Mg‐3 .52Sn alloy ,respectively ,then decrease slightly ,and finally increase to 92 MPa and 15 .5% again for Mg‐6 .54Sn alloy ,respectively .After solution treatment ,Mg2 Sn phase dissolves into α‐Mg matrix com‐pletely .The tensile mechanical property is enhanced slightly and remains almost unchanged at ambient and elevated temperatures ,respectively .T he impact toughness is reduced and enhanced for the low and high Sn contents ,respectively .%分析了铸态和固溶态Mg‐xSn（x＝2．18～6．54）合金的组织，测试了其拉伸力学性能、硬度及冲击韧性．结果表明，随着Sn含量的增加，铸态组织中粗大树枝晶状α‐M g逐渐细化，M g2 Sn相逐渐增多，并且趋于连续网状分布于晶界处．室温下合金铸态拉伸力学性能及冲击韧性表现为先提高后降低，具有最佳性能的Mg‐3．52Sn合金的抗拉强度σb 、延伸率δ和冲击韧性值αnK分别为151 MPa ，12．5％和10 J／cm2；高温（423 K）时σb和δ先分别逐渐提高至Mg‐3．52Sn合金的87 MPa和19．0％，经略有降低后又分别逐渐提高至Mg‐6．54Sn合金的92 MPa和15．5％．经固溶处理后，Mg2Sn相完全固溶于α‐Mg基体中；室温下拉伸力学性能有所提高，而高温下拉伸力学性能基本保持不变；在Sn含量低和高时冲击韧性分别降低和提高．
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