Abstract: The incidence of gastrointestinal malignancies is high in the population, and 40%‒80% of gastrointestinal tumor patients suffer from malnutrition. The metabolic mechanism of tumor disease itself, and the perioperative stress reaction caused by surgical treatment can further aggravate malnutrition. Therefore, nutritional support should be routinely provided during the perioperative period in tumor patients with nutritional risk or malnutrition. For a long time, immunonutrients such as glutamine, ω‑3 fatty acids, arginine and nucleotides have attracted much attention in the treatment of perioperative tumor patients. Most studies have shown that perioperative immunonutrition therapy not only improve nutritional deficiency and correct malnutrition, but also maintain immune function, reduce inflammation and maintain intestinal barrier integrity, to reduce postopera-tive complications and short postoperative duration of hospital stay. However, with the extensive clinical application and in‑depth study of immunonutrition in recent years, there are still many doubts and controversies about its application in the perioperative gastrointestinal malignancies. The authors review the pharmacological mechanism and clinical application of perioperative immunonutrients, perioperative combined application of immunonutrients, and application timing and approach of immunonutrition in patients with gastrointestinal malignancies, so as to provide some clues for its subsequent clinical application.