Abstract: Welded seam identification is the major purpose of X-ray defect recognition technique for the spiral welded pipe.Based on the MATLAB image toolbox IPT, and according to the characteristics of the X-ray image of the spiral welded pipe, welded seam segmentation is implemented by means of median filtering, ROI shielding pretreatment, and using the image gradient and probability to calculate the weld centerline which is then further refined.Finally, the recognition algorithm is described with actual examples, and the applicability of the X-ray weld seam recognition method is analyzed.