We demonstrate a novel method to segment the tongue image automatically with the mouth location method and active appearance model (AAM). With the help of a particular feature of the mouth,we could locate the dark hole's position easily and quickly. For the close relationship between the mouth and tongue, we would predict the approximate area of the tongue. Then we apply the AAM to segment the tongue from the image completely, which uses texture and shape of an object. During the AAM search, we constrain the initial displacement and size in the approximate area. For those images that failed to locate the mouth, we use a multi-initial displacement method during the AAM search to optimize the result. The experiment shows that our method is accurate and effective.