Effects of aging treatment on microstructure and mechanical properties of lead-free and free-cutting Al-Mg-Si alloy contained minor Sn and Bi were investigated during solid-solution and cold drawing process by tensile testing, XRD （X-ray diffraction）, SEM （scanning electron microscope） and EDS. The results show that, the optimized aging treatment is treated at 170℃ for 8 h. The alloy with Sn addition only is composed of Al matrix and Mg2Sn as well as AlMnSi phase, while the alloy with Sn and Bi addition is composed of Al, Mg3Bi2 and AlMnSi phase as well as minor Sn and Bi phase.