Abstract: 7XXX Al-Zn-Mg-Cu alloys are a type of widely applied high strength aluminum alloys, and their welding is a critical challenge in engineering applications. Tungsten inert gas (TIG) welding is the main method of aluminum alloy arc welding, in which the welding current is an important factor affecting the quality of the joint. In this paper, butt welding tests were carried out on 7075 aluminum alloy plates by TIG welding with ER5356 welding wire as the filling material, and the microstructure and mechanical properties of 7075 aluminum alloy TIG welded joint welded at different welding current were studied, and the effects of different welding currents and post-welding heat treatment on the microstructure and mechanical properties of the welded joints were investigated. The results show that the transition zone between the heat-affected zone and the nugget zone of TIG welded joint is narrow, with no obvious interface or inclusion enrichment was formed. The nugget zone show a typical as-cast solidified structure, which consists of α-Al equiaxed dendrites and intercrystalline second phases. With the increase of welding current, the size of α-Al grains increase gradually, and the contents of Zn, Mg and Cu elements all increase first and then decrease. After the post-welding heat treatment at 480 ℃×1 h+120 ℃×24 h, most of the coarse second phases disappear, the main alloying elements distribute uniformly, and the α-Al grains do not coarsen significantly. Before and after post-welding heat treatment, the tensile strength and elongation after fracture of 7075-T651 aluminum plate TIG welded joint both increase first and then decrease with the increase of welding current, and this trend becomes more obvious after heat treatment due to precipitation strengthening.