动态包络算法在希望获取目标的精确轮地是经常使用的一个算法，但在以往的Snake算法中，由于没有考虑到其总体的形状因素，加之一些干扰的影响，其包络点很可能收敛于错误的位置。

The active contour model, as known as‘Snake’,is often used when one wanted to get a precise contour of an object in image processing field. The Snake algorithms known before often converge to a wrong result because they have not used the whole shape factor in the procedure of finding“minimum energy position”. This problem becomes more serious in some fast algorithms (these fast algorithms were usually obtained by decreasing the relation of Snake points). In this paper, a new active contour model based on a typical fast algorithm of Snake is proposed. Because the new algorithm considers the whole shape factor, the relationship among the Snake points is stronger than before and the reliability of computing result is improved. The effectiveness of the new algorithm is confirmed by the experiment in the end of this paper.