It is difficult to select the threshold and sometimes it introduces many disturbance edges in edge detection.Aiming at these problems，an interesting edge detection algorithm is proposed.The algorithm has four steps.Firstly，the image is smoothed to de-noise.Then，gradient magnitude image and gradient direction image are calculated.After that，gradient magnitude image is filtered according to gradient direction image.At last，gradient magnitude image is segmented to get initial edges，and the edge mapping images are traced.Experiment results indicate that this algorithm has good applicability.