Abstract: An automatic recognition and welding seam-tracking visual method was proposed.Different from the active vision method using the macrostructure feature of the workpiece, the passive vision method the gray gradient of the workpiece image is used, It uses the obvious difference of texture feature between welding seam region and base metal region.It has advantage to solve the weld recognition in the multi-layer welding, which is diffcult for the usual visual method.In the method, the textural feature of the image was firstly analyzed, and then the image was segmented by the difference of the image texture feature between the weld region and the base metal region;finally, the zone of the weld were recognized, and its position and the center could be found.Experiment showed the proposed method was effective for welding seam recognition in multi-layer welding.