The principles of enteral nutrition support: first of all, the patient has malnutrition, and the patient is assessed as being at nutritional risk and having malnutrition. This assessment is scored, and there are three aspects of the score: one is the age status, one is the chronic disease status, and one is the nutritional risk status. The nutritional risk depends on whether the patient has recently lost weight, whether the body mass index has fallen very low, and whether he has eaten well in the last week, and whether he can achieve 25-30kcal per kilogram of body weight per day according to the ideal weight, if it is not enough, the patient has good gastrointestinal function, or he has done a large part of gastric resection, but the function of the intestine is very good, and the function of the jejunum is very good. Nutritional support therapy is available, and the preferred method is enteral nutrition. The first choice is enteral nutrition. In nutrition support therapy, there is a saying: as long as the intestine is functional, enteral nutrition can be given, no matter when it is.