For providing reliable guides to optimize welding processing technology, it is an effective way to utilize segmented moving heat source model and similitude method based on elastic strain energy synthetically. A big challenge, the accurate controlling of welding-induced distortion in the beam of the huge bridge crane for Three Gorges project, is achieved successfully with the proposed approaches. First, numerical simulation and model experiments for some selected important factors are made at the same time. If the results acquired through both ways are accordant, then other factors can be analyzed reliably by the same numerical method. Thus, a complete set of instructions can be received for the real processing. The practical application proves that the numerical method combined with physical experiments can enhance the manufacturing level of welding structures evidently.