Lightweight Aluminum alloys, particularly 5xxx series Al-Mg alloys, are now widely used in aerospace, maritime, and automotive industries due to the superior strength-to-weight ratio, excellent corrosion resistance and recyclability. Mg has a high solubility in the Al matrix and solute Mg can appreciably improve the work-hardening ability of Al-Mg alloys. In this study, effects of Mg addition in the rolled Al-xMg-0.12-0.12Cr based alloys with thin sheet (0.2mm) on microstructure and mechanical properties. In first, Al-xMg-0.12-0.12Cr (x = 2, 4, 6, 8, 10 and 12wt.%) alloys were prepared by gravity cast process. This Al alloys were hot-extruded into a sheet that was 4mm in thickness and 50mm in width at 500℃. The extruded alloys were rolled with a thickness of 0.2 mm at room temperature. The microstructure of specimens was examined by OM, XRD, SEM and EBSD. The mechanical properties of the Al alloys were maintained by a tensile test.