Abstract:The structure of the digestive tract in Platypharodon extremu was studied by the methods of anatomy, histology and microscope technology. The results are as follows:The digestive tract of Platypharodon extremu shows the characteristics of herbivority fishes are typical of lower mouth, small crack, and no teeth in the mouth. Meanwhile there was a developed cuticle in the jaw. The esophagus having well-developed plica mucosa is stout and short. The gut is relatively long and zigzaggingly complex. The morphology index of the number of mucosal folds, columnar epithelium height and the thickness of ring and longitudinal muscle, is discriminative in the different parts of the gut. The results suggested that the intestine function is not the same in the different parts. Also discussed are the segments of the intestine, histological features of the alimentary tract of this species, and their relation with the eating habits of the humphead wrasse.