Abstract: The 7075 aluminum alloy sheet with thickness of 10 mm was welded by VPPA vertical welding process using ER5183 welding wire. The microstructure and mechanical properties of the welded joint were comparatively investigated by means of optical microscope (OM),scanning electron microscope (SEM), X-ray diffraction (XRD),universal tensile testing machine and micro-hardness testing machine. Experimental results indicate that the finally welded products exhibit an excellent welding appearance, and have no obvious fusion zone, the microstructure of heat-affected zone is coarse, the hardness value of welded joint and heat-affected zone are 120.9 and 125.9, respectively. The tensile strength of the welded joint reaches 367.6 MPa, which is nearly 62.4% of the parent metal and corresponds to the weakest segment of the welded joint.