Abstract: The microstructures and corrosion properties of 5083 aluminum alloy friction stir welding(FSW) and MIG(metal inert-gas) weld were analyzed. The results showed that the FSW weld was characterized by its much finer grains, contrasting with the grains of MIG weld. Electrochemical corrosion test demonstrated that the corrosion potential of the FSW weld at the rotation rate of 300 r/min, and the traverse speed of 160 mm/min with 3° tool tilt was more positive than that of the MIG weld, meanwhile, the corrosion rate and the corrosion current density were less than those of the MIG weld, Rp(polarization resistance) of the FSW weld was larger than that of the MIG weld. The corrosion morphologies analysis showed that few shallow pits presented on the surface of the dissimilar weld. However, a large number of deeper pits emerged on the surfaces of two parent materials.