Enzyme analytical method was used to investigate the activities and distributions of protease, amylase, cellulase in straight intestine, middle intestine, inner intestine, digestive gland, stomach and crystalline from three different styles of Hyriopsis cumingii. The morphology and structure of crystalline style were also examined by paraffin section, light microscopy, scanning and transmission electron microscopy. The results showed that the relationship among digestive enzymes activities in all the six kinds of digestive organs was amylase＞cellulase＞protease, and amylase activity was significantly higher than cellulase and protease. Both protease and amylase activities were significantly higher in crystalline style, while cellulase activities were higher in stomach and orstraight. In contrast to a marked rise in protease activity, the amylase and cellulase demonstrated pronounced decreasing trend accompanied by the increasing wet weight of Hyriopsis cumingii. Compared to the solid line of crystalline style under starvation, a food channel was formed when Hyriopsis cumingii was full, which circumgyrated in one direction to mill, separate, enwrap food and digested them finally.