Ileostomy is a common procedure in surgical practice. After this procedure, the patients may be in a state of relative fluid depletion due to the increased fluid and electrolyte losses resulting from the loss of colonic absorption. Within weeks after ileostomy creation, there is a body adaptation process of increased fluid absorption. However, some patients will fail to adapt adequately and have a large volume of ileostomy output, or will develop ileostomy diarrhea due to other causes. Many patients with ileostomy diarrhea are at risk of dehydration and electrolyte loss, and often require hospital readmission, which consumes a lot of medical resources. Except for the mastery of surgical skills of ileostomy, surgeons should fully understand its pathophysiological processes, so as to allow the implementation of targeted treatment. Here, the authors address the pathogenesis and treatment of ileostomy diarrhea, hoping to provide a reference for the treatment of patients with this condition.