Abstract: It is hard for the traditional robotic portraying technology to represent the extracted nose contour, thus influencing the encoding and vectorization for the nose. Hence, a nose contour extraction algorithm has been presented based on the least square method. Firstly, the nose tip and nostrils are positioned after the nose has been detected. Then the key feature points are positioned, and the contour reference points are searched by constraining and controlling the key feature points. At last, the nose contour curve is fit based on the least square method, thus obtaining the nose contour curve. Experiments show that our method can effectively extract the features of nose contour and also facilitate the encoding and vectorization.