Abstract: 7055 aluminum alloy billet was prepared by spray forming, and then extruded and drawn into an aluminum alloy welding wire with a diameter of 1.2 mm. The welding wire was used for automatic MIG welding of 3 mm thick 7075 aluminum alloy sheet. The microstructure and properties of the welded joints under different currents were analyzed. The results show that when the 7075 plate is welded by using self-developed 7055 aluminum alloy welding wire, the weld seams are well formed. The weld zone is mainly dendritic network structure, and the grain boundary in the weld zone becomes coarse with the increase of current. The fusion zone is mainly composed of irregular dendrite and columnar structure. The main precipitated phases of the weld zone are η-（MgZn₂）, Al₃Zr and S-（Al₂CuMg） phases, and a small amount of σ-（AlFeSi）impurity phase exists. The average microhardness of the weld zone of the 70A welded joint is 107 HV, the tensile strength of the joint is 294.08 MPa, and the elongation is 7.5%, showing the characteristics of ductile fracture, and the overall properties are excellent.