Abstract: Automatic detection of the weld shape is achieved by computing the shape of the weld according to the gradual variation of shading in the image of weld snapped by industrial charge coupled device, and improved the efficiency of detection greatly. The paper processes the images of weld by shape from shading in computer vision, implements it with iteration scheme and speeds the computing process through hierarchical structure. Experiments show that the technology has the apparent advan lages: simple to install devices, lower cost, easy to implement and high precision, and the tochnology provides background for the inteliigence and automation of weld shape detection.