Abstract: In this paper, the weld area extracting in automatic recognition for weld defects had been investigated according to the feature of weld seam image. Based on the above, defects rectangle and end rectangle were defined for shape and size of defects correcting. Defects rectangle forming, cycle of segmentation and growth, defects dege extracting were designed. A satisfactor results were obtained on weld area extracting and a high fidelity of defects was gotten.