Abstract: A thermal coupling numerical model was established for double-wire MIG welding of 7A52 aluminum alloy, based on the finite element software ABAQUS, and the welding residual stress field was obtained. A coupling model of ultrasonic impact treatment on the welded joint was built with numerical method and the residual stress field was obtained after ultrasonic impact treatment. The distribution characteristics of residual stress before and after ultrasonic impact and the influence law of residual stress by changing the needle moving speed were analyzed, aiming to study the effect of ultrasonic impact using on residual stress of 7A52 aluminum alloy joint. The simulation results show that the ultrasonic impact treatment could significantly improve the surface residual stress of weld seam and heat-affected zone, and the compressive stress in welded joint decreased with the increase of impact moving speed.