Abstract: Hierarchy analytical theory combined with the experiment is employed to determine the weld bead stability synthesis evaluation weight coefficient of weld surface quality, weld reinforcement and weld width of weld bead.The membership degree tables of surface quality, weld reinforcement and weld width are created by fuzzy theory.The analytic hierarchy theory and the fuzzy mathematics are applied to evaluate practical bead stability.The results show that the calculation value accords with the actual result, which proves the method of bead stability evaluation is effective.