Postoperative diarrhea after abdominal tumor surgery is a common postoperative complication of gastrointestinal surgery, often associated with damage to the intestinal mucosal epithelium during a 24-hour fast, disturbance of intestinal flora, antibiotic therapy, and acute severe gastrointestinal stress. Diarrhea can be caused by sudden administration of hypertonic drugs and enteral nutrition preparations after prolonged fasting (e.g., whole protein-type enteral nutrition preparations, magnesium-containing antacids, sorbitol-containing preparations, electrolyte supplements). Modification of drug administration, adjustment of food and enteral nutrition solution concentration and osmolarity can improve diarrhea. The addition of fructose oligomers, pectin and other soluble dietary fibers can also help in the treatment of diarrhea. For patients on tube feeding (nasogastric tube, nasal-enteral tube), low osmolarity enteral nutrition preparations and protein predigested enteral nutrition preparations can also be used.