The laser molten pool model was built to research the influence of high-frequency ultrasound vibration (HFUV) on aircraft thin-walled structures using the COMSOL software. The acoustic pressure of the laser molten pool was simulated considering the position and number of sources, with both side-touch single vibration and dual vibration sources being used. The results indicate that the positive and negative acoustic pressures alternate with HFUV, and the temperature field is homogeneous. This phenomenon favors the generation and collapse of cavitation bubbles, resulting in the ultrasound cavitation effect and reduced residual stress. The distance and amplitude of the ultrasound are directly proportional to the acoustic pressure of the molten pool. The acoustic pressure of the molten pool will enlarge 2-3-fold with each 10-mm decrease in the distance from the ultrasound loading position to the molten pool and by 10 Pa with each 4-?m increase in the amplitude. HFUV primarily acts as a blender for the molten pool. The acoustic streaming effect will appear when the amplitude exceeds 7 ?m and the distance is lower than 60 mm. The ultrasound cavitation effect dominates when the distance is lower than 15 mm. Dual vibration sources will not influence the acoustic pressure amplitude of the molten pool. Still, the gradients of acoustic pressure influenced by these conditions will be favorable for the homogeneous flow of metal liquid on the sides of the molten pool, achieving the aim of grain refinement and reduced residual stress.