Abstract: The welding stress and distortion which are induced bynon-equilibrium heat and cool process have serious effects on welding process and the service behavior of welded structures,and is one of the key techniques in the process of production and manufacture of welded structures.This paper has summarized the prediction of 3-D welding stress and distortion,controlling,numerical simulation technique,combining with our the researching work,the difficulties and problems to be solved in the prediction of welding stress and distortion of large and complex welded structures have presented,and several examples applied in engineering have been introduced.