The recognition and category of the flaw of Copper Clad Laminates were achieved in this paper. Prewitt edge detection algorithm and histogram analysis were used to pre-process of the images. Edge pixels were tracked by Freeman chain code. According to chain code table , the coordinate of edge pixel can be used to calculate some parameters of the shape character , such as the length , width and area of the aim , especially the circle alike parameter. These methods were effective and credible.