An　application　of　Immune　Genetic　Algorithm　(IGA)　suitable　for　the　optimal　design　to　intelligent　AC　contactors　is　presented　in　this　paper.　Besides　the　ability　of　stochastic　global　searching　of　Simple　Genetic　Algorithm　(SGA),　t　he　IGA　draws　into　the　mechanisms　exist　in　biological　immune　system　such　as　immune　memory,　immune　regulation,　antibody　diversity　and　others.　The　simulation　results　show　that　IGA　overcomes　the　disadvantages　of　premature　convergence　of　SGA,　and　improve　the　global　searching　efficiency　and　capability.　This　algorithm　has　been　successfully　used　in　the　optimal　design　to　the　intelligent　AC　contactors.　©　Springer-Verlag　Berlin　Heidelberg　2006.