Abstract: A new method was introduced to accurately detect the defects of time of flight diffraction (TOFD) D scanning image. First, the clutter suppression algorithm based on energy distribution was used to remove direct wave and reflected bottom wave. The background clutter could be removed through algorithms of binarization processing, edge detection,corrosion, clustering and removal of small clusters. Then, a parabola was fitted through the least square method, and ordinate vectors of feature points and fitted points were on the correlation processing. With the matching degree of defects and parabola, the defects could be detected. The results demonstrate that the proposed method was effective and accurate.