Abstract: In target detection and recognition from sonar images, recognition of mine target is a key technique. Based on the concept of shape similarity, a novel method for mine shape classification is proposed. Shallow region of mine is extracted and normalization. Modified shape context method is adopted to classify contour of mine targets. Compared with the conventional shape context method, the modified version has characteristics such as rotation invariance and template adaptive renewing. Simulation is performed to classify spheres, cylinders, and tapers, with a ratio of correct classification 92.7%. Results indicate that this method is affine-transform invariant and has high precision.