Face contour extracted by most existing extraction technology has the problem of non-smooth. Aimed at this situation,an segmentation modeling method for head-face contour is proposed. The piecewise function model is established using hyperelliptic curve,elliptic curve,circular curve and parabolic curve according to points definition and segmentation of contour. Contour sample's parameters obtained from the processing and optimization of 100 real human head-face images which contains five kinds of face verify the effectiveness and universality of the model. The result shows that the average error is under 1.2% and the maximum error is under 2.6% for each sample after optimizing the model. Finally the range of model parameters corresponding to each type of face is given by face shape classification based on the mathematical model.