Abstract: In order to solve the problem of easy deformation and large deformation of 6061 aluminum alloy in the laser welding process, ultrasonic assisted laser welding experiment was carried out with 1mm thick 6061 aluminum alloy sheet as the research object to explore the inhibition effect of ultrasonic on welding deformation of 6061 aluminum alloy. The influence of ultrasonic power on welding deformation was analyzed by single factor test method. Five factors and five levels orthogonal test including ultrasonic power, laser power, welding speed, defocusing amount, and shielding gas flow wer designed. The influence degree of ultrasonic power and conventional welding parameters on welding deformation was analyzed, and the process parameters combination which can obtain the minimum deformation were obtained. The results show that the welding deformation decreases with the increase of ultrasonic power, and the bending deformation and angular deformation of the specimen are reduced by 51.27% and 51.46% respectively when the ultrasonic power is 800W.At the same time, when the laser power is 1000W, the welding speed is 5m/min, the defocusing amount is + 1mm, the shielding gas flow rate is 15L/min, and the ultrasonic power is 800W, the minimum deformation of the specimen can be obtained, and the bending deformation is 0.42mm, and the angular deformation is 0.26mm. This study provides a certain technological and theoretical reference for the application of ultrasonic assisted welding in controlling welding deformation of thin plates.