The butt joining of 2 A14 aluminum alloy to 5 A06 aluminum alloy was conducted by TIG welding with BJ380 A,5 A06 and2325 aluminum alloy filler wires,and the microstructure and mechanical properties of the joints were analyzed. The results show that there are no cracks and pores in welds. The grain growth in the heat-affected zones（HAZ）near 2 A14 base metal is more obvious than that near 5 A06 base metal,and the grain is coarser in the weld made with BJ380 A filler wire than that in the weld made with 5 A06 or2325 filler wire. The tensile strength of joints is dissimilar by three filler wires,and the lowest value is about 83% of that of the 5 A06 aluminum alloy base metal. The tensile strength of the joint obtained by 2325 welding wire is the highest. Fracture analysis shows that the fracture of 2325 welding wire joint is ductile fracture,and the fracture is mainly dimple.