Many patients have preoperative malnutrition, and there may be many reasons why preoperative nutritional support therapy is not or cannot be administered. The combination of surgery, infection and tumor leads to continued worsening of malnutrition and eventual development of ascites, lower limb and low hanging site edema. Those with severe anemia and hypoproteinemia have priority to correct hypoproteinemia and anemia. However, hypoproteinemia cannot be modified by simple infusion of albumin or plasma without nutritional support therapy. In the presence of ascites, it is advisable to record daily in and out volumes, aiming for more out than in. The intake should be limited to 1500 to 2000 ml and the output should be 2800 to 3300 ml. If the above trend is followed, there should be a turnaround after 3 days. If there is no obstruction in the digestive tract, enteral nutrition therapy should be resumed as soon as possible while the systemic edema subsides. Enteral nutrition therapy is both safe and efficient, and should be the first choice of nutritional support therapy. Enteral nutrition therapy requires the establishment of an enteral nutrition route, which can be done by placing an enteral nutrition tube under gastroscopy or X first, or by open gastrostomy (suitable for those who cannot eat due to esophageal cancer and oropharyngeal diseases) or jejunostomy (suitable for gastric lesions). Enteral nutrition therapy should pay attention to three degrees: appropriate temperature (38~40℃, can be preheated by hot water or heated by heater), appropriate speed (uniform drip, start slowly, gradually adapt and gradually increase the amount), and appropriate concentration (50% dilution with saline or sugar saline for initial use, can be gradually overdosed to the original solution). To reduce diarrhea, you can take compound phenylephrine tablets, two in the morning and two in the evening. A variety of enteral nutrition solutions are available clinically, such as Nengxiang, Rexin, Risu, Bepril, etc. In order to improve the efficiency of nutritional therapy, synthetic-promoting drugs such as insulin and growth hormone can be used along with nutritional therapy, and glutamine preparations can also be added. This so-called metabolic conditioning. Figure 1, the optional Fulcrum enteral nutrition tube Figure 2, the placement of enteral nutrition tube under X-ray. The enteral nutrition tube has already entered the duodenum and will then enter the jejunum. Figure 3, the enteral nutrition tube has been placed under X-ray Figure 4, enteral nutrition therapy is performed