Abstract: Using ABAQUS finite element analysis software, the thermodynamic model of 7075 aluminum alloy laser welding was established. Then, the numerical transfer method was used to carry out UIT on the joint, and the coupling model of welding and UIT was established. On this basis, the thermodynamic model of aging treatment was introduced to establish A-UIT treatment model after welding, and the distribution and characteristics of residual stress under different treatment were analyzed in order to study the effect of different treatments on the improvement of welding residual stress field of 7075 aluminum alloy. The results show that A-UIT treatment can significantly improve the residual stress in the weld and its adjacent area. The residual tensile stress in the center of the weld changes from 180.21 MPa to −150.26 MPa, and the conversion rate is as high as 183.4%. Compared with the single ultrasonic impact treatment, A-UIT treatment can alleviate the residual tensile stress concentration near the direct impact zone.