The invention relates to a laser welding method for ultrasonic vibration along with welding, and belongs to the field of welding. According to the method, preheating is applied in the welding process,and ultrasonic vibration is applied to the front side of a weld joint at a certain distance behind a molten pool; a corresponding relation exists between the preheating temperature T and the distanced from the top end of an ultrasonic head to the welding position, wherein the relation expression is as follows: T is equal to 30d-40, the unit T is DEG C, and the unit d is mm; and the position, thepower and the force of ultrasonic application are adjusted according to the mechanical property of materials under the preheating temperature. According to the laser welding method, the welding residual stress can be effectively reduced, pores and cracks are reduced, and thus the fatigue performance of the weld joint is improved, and the welding deformation is reduced. By adopting the method, thetemperature gradient in the cooling process can be effectively reduced, and the residual stress is reduced; and the plasticity of the ultrasonic application area can be improved, and the ultrasonic effect is better. The ultrasonic impact can effectively reduce residual stress, refine crystal grains and reduce pores and cracks, and thus the fatigue performance of the weld joint is improved; and the metal plastic extension of the weld joint can effectively reduce the welding deformation.