The laser welding head is integrated with the CCD video tracking module, and a method for automatic seam detection based on a word line laser is proposed. This method uses laser triangulation to obtain the height, width, and other shape information of the weld. In the aspect of image processing, we perform median filtering and binarization on the obtained weld area image to obtain the two-dimensional coordinates of the weld feature points, achieve target position and calculate its three-dimensional coordinates in the world coordinate system. In the tracking algorithm, we use high accuracy and high speed kernel correlation filters target tracking algorithm to track the positions of common straight and curved welds. The verification experimental results show that the fitting curve and weld shape error are within 5%, the degree of coincidence is high, and the real-time tracking effect is good.