Abstract: AC-TIG welding was performed on 2A12 aluminum alloy,the effects of ER4043 and BJ-380A welding wires on microstructure,tensile strength and hardness of welded joints were discussed.The results show that the typical cast dendrite was obtained in the weld seam zone of the joints with the two types of welding wires,and the grain growth direction was perpendicular to the welding direction.Compared with ER4043 welding wire,more strengthening phases precipitated at grains boundaries at heat affected zone of the joint with BJ-380A welding wire.The tensile strength of the both welded joints are over 50% of the base metal,and the fracture positions all were located on heat affected zone.Compared with BJ-380A welding wire,the strength and hardness of the joint with ER4043 welding wire were higher,and its tensile strength up to 67.9% of the base metal.