The　effect　of　the　different　electromagnetic　stirring　frequency　after　low　temperature　pouring　on　microstructures　and　mechanical　properties　of　Al-7Si-0.42　Mg-0.1Cu　alloys　was　studied.　It　was　found　that　the　primary　α-Al　becomes　smaller　and　tended　to　be　spherical　morphology,　and　the　particles　were　uniformly　distributed　after　electromagnetic　stirring.　The　tensile　strength　of　alloys　improved　gradually　from　193.02　MPa　to　212.54　MPa,　and　the　elongation　increased　from　3.73%　to　6.67%　when　the　stirring　frequency　was　10　Hz.　From　the　fracture　morphology,　the　fracture　for　alloy　stirred　at　frequency　of　10　Hz　showed　more　dimples　than　that　without　stirring.　When　the　stirring　frequency　increased　to　15　Hz,　the　microstructures　of　primary　α-Al　appeared　to　be　dendritic　structures,　and　the　grains　became　coarse.　As　a　result,　the　10　Hz　was　the　best　electromagnetic　stirring　frequency.　©　2017　Trans　Tech　Publications,　Switzerland.