Abstract: In many practical fields, image segmentation is the most important procedure. The purpose of image segmentation is to detect the objects in images. The methods based on statistic theory can work well on images with no noise or little noise. But the procedure of segmentation is difficult to be obtained and the accuracy of result often depends on some artificial parameters. A lot of physical phenomenon can be described by Partial Differential Equations (PDEs) and related procedure is easy to be displayed. With the applications of PDEs, it is convenient to accomplish segmentation and represent the procedure.