Early intravenous nutrition therapy for feeding intolerance in premature infants Sepsis in 2 cases, metabolic acidosis in 3 cases, necrotizing enterocolitis in 2 cases, hyperbilirubinemia in 3 cases. There was a significant difference in the incidence of total complications between the two groups (x2=4.69, P170μmol/L and serum albumin <25g/L, fat emulsion would affect bilirubin metabolism. As long as there is sufficient albumin supply, small amount application and slower infusion speed would not affect bilirubin metabolism. Medium and long chain triglyceride fat emulsion could stabilize the metabolic environment of preterm fat and provide energy, reduce fat accumulation, and avoid elevated blood lipids. The data of this group showed that using early intravenous nutrition, from the first day after birth, amino acids and HL were used gradually up to full amount, which could provide the needed nutrition as soon as possible. The amplitude of weight gain in the treatment group was significantly higher than that in the control group, shortening the physiological decline period of body weight and better promoting the growth and development of the infant. With the increase of body weight, gastrointestinal feeding can promote the establishment of normal intestinal flora, promote the secretion of gastrointestinal hormones, promote gastrointestinal peristalsis and gastrointestinal development maturity, increase tolerance to gastrointestinal feeding, shorten the application time of intravenous nutrition, enhance local antioxidant capacity of the gastrointestinal tract and reduce the damage of oxygen free radicals to cells, and play a protective role in the immature gastrointestinal mucosa of premature infants. Early feeding also helps the excretion of bilirubin in feces and reduces enterohepatic circulation. Breast milk contains abundant immunologically active substances, anti-inflammatory factors and immune modulators, which can enhance the immunity of premature infants. Non-nutritive sucking can stimulate the vagus nerve excitement of oral fibers, increase the level of gastrointestinal hormones, accelerate gastric emptying, and shorten the transition to full gastrointestinal feeding. Early intravenous nutrition provides comprehensive and adequate nutrients as soon as possible for premature infants with gastrointestinal nutritional intolerance, making the body weight of premature infants increase rapidly, quickly passing through the physiological decline period of body weight, reducing the number of days of intravenous nutrition and hospitalization time, without serious side effects, which is a safe and feasible method of intravenous nutrition.