Parenteral nutrition support refers to the supply of multiple nutrients via intravenous route to ensure the nutritional needs of pre- and post-operative and critically ill patients, and the total nutrition is supplied from parenteral nutrition (total parenteral nutrition, TPN). Its indications include gastrointestinal obstruction, absorption dysfunction and gastrointestinal failure. The department has been tracking the latest development at home and abroad, and now it is one of the best units in Nanjing in standardized parenteral nutrition technology. 1. Standardized nutrition solution preparation: With the support of the dispensing room of pharmacy center, the department has successfully carried out the “total parenteral nutrtion” technology. The daily required nutrients (glucose, fat milk, amino acids, electrolytes, vitamins and trace elements, etc.) are mixed in one bag on the ultra-clean dispensing table certified by GMP to make “all-in-one” nutrition solution. The advantages are: (1) it meets the physiological requirements and facilitates protein synthesis; (2) it reduces metabolic complications such as hyperglycemia and electrolyte disorders; (3) it reduces the concentration of individual nutrients and reduces the osmotic pressure of the nutrient solution, thus reducing intravenous irritation; (4) it reduces blood glucose concentration, which facilitates blood glucose control and reduces infection complications; (5) it reduces contamination (toxins, bacteria, fungi, impurities) of the preparation; and (6) it is convenient for infusion and reduces impurities. (6) facilitate infusion and reduce nursing work intensity. 2. standardize the infusion route: for this reason, our physicians have practiced excellent central venipuncture techniques, so that they can reasonably choose various ways of infusion, such as central vein, PICC or peripheral vein, to reduce infusion-related complications. 3. standardize the use of special nutrients: the application of some special nutrients in the perioperative period has been proven to improve patient prognosis. For example, glutamine dipeptide can effectively protect the intestinal mucosal barrier, improve immune function and promote incision healing; the use of fish oil fat milk instead of partial long-chain fat milk can inhibit inflammatory response, reduce SIRS, reduce infection complications and shorten hospitalization time. Our department has carried out research on “fish oil fat milk for post-operative liver transplant patients”, and has applied many special nutrients such as glutamine dipeptide and fish oil fat milk to major surgery and critical patients, and achieved remarkable efficacy.