This thesis takes Al-7Si-0.3Mg casting aluminum alloy as the research object, adding 0.2~0.6% Sc element during smelting to investigate the effect of adding Sc in Al-7Si-0.3Mg aluminum alloy, including the research on different aging treatments temperature and time for the mechanical properties and microstructure of Al-7Si-0.3Mg aluminum alloy. The results show that adding an appropriate amount of Sc (wt 0.4%) and a suitable aging treatment temperature and time (195℃×4Hr) can indeed increase the tensile strength (296 MPa) and hardness (HRB 63) of Al-7Si-0.3Mg aluminum alloy.