The study on nutritional characterectics of helmet catfish (Cranoglanis bouderius Richardson, 1846) in Nghe An Province has some highlight results as follows: i) For the structure of digestive system of helmet catfish, their mouth locates under toward with curved shape, upper jaw longer than lower-jaw. Molar teeth are like villus matterial, curved, elongated, shrinked toward the rear, and interrupted in the middle. The short esophageal tube has a thick wall. The interious of the esophagus has many folds which are able to stretch, so the fish can swallow large preys. Its stomach is J-shaped, large, thick-walled, and has many folds so that it can strongly expand and shrink. The gut of helmet catfish is folded and short with a thick wall; ii) For the nutritional characterectics of helmet catfish, this is an omnivorous species, which has a high frequency of sufficient food at levels of 1, 2, 3. The ratio between the intestine and the fish length was on the average of 1.23.