Abstract: It can remove residual welding deformation effectively to use technology of restraint welding and reverse deformation. But, it is very difficult to calculate values of restraint, restraint length and reverse deformation accurately, because of the complication of stress and strain fields in welded structure. By the theory of elasto-plastic bend, this paper prowents a method to calculate out-of-plane restraint and reverse deformation that are made use of to remove angle deformation in butt joints. The values of limit restraint, restraint length and reverse deformation have been calculated. The results of test show that the calculation method is effective.