Wavelet analysis is advantageous in detecting edges. This paper presents a systematic study on V groove welding laser image and the seam recognizing method of multi pass welding image. We propose a seam recognizing algorithm based on wavelet transformation and an algorithm to recognize the corner tracking in a multi pass V groove. According to the characteristic of multi pass V groove

our algorithm outperforms the algorithm of seam recognition in V groove and uses the technology of template matching

can recognize the corner tracking.