The requirement of stress-relief heat treatment for Nuclear Power Plant steel containment vessel（CV） is demonstrated,and the advantages and feasibility of replacing heat treatment with ultrasonic regulation are analyzed theoretically. The mechanical properties and residual stress distribution on weld state,heat treatment state and ultrasonic regulation state are compared and analyzed. The results show that the residual stress of the joint can be effectively reduced by ultrasonic,and the average stress relief rate reaches 24.4%. The stress reduction effect of ultrasonic regulation for 2 hours is similar to that of heat treatment for 10 hours. At the same time,there is no obviously deterioration in tensile strength,elongation and impact properties of the joint under ultrasonic regulation. It is considered that the ultrasonic regulation technique could replace the stress-relief heat treatment,and the direction of further research is given.