Abstract: This paper describes the structure of crystalline style of a freshwater clam(Anodenta woodiana) with scanning. electronic microscope (SEM). The results showed that the shape of crystalline style is same as column. The crystalline style of the clam could be divided into head and rob parts. The former is also divided into two sections. The head is winding slightly, forming an acute angle with the rob. The surface of the head was with honeycomb-like membrane, in which there were a great of enzymatic granule and mucus. The later was trough on both of the rob and had many hollows. The hollows are round or oval shape, which are different in size、depth and irregular in arrangement. Beside, they are also rough on the other surface of the rob. The function of the crystalline style is major of mixing and digesting food. The relationship between the structure and function of the crystalline style was also discussed.