Background: Prophylactic ileostomy and colostomy have been widely used to reduce the risk and complications of anastomotic leakage with high-risk colorectal cancer after operation. However, prophylactic ileostomy itself has some complications, and ileostomy high out-put syndrome is one of them. This study was performed to explore the risk factors of HOS in ileostomy.Methods: A total of 114 patients with HOS were screened out from 494 eligible ileostomy patients in the last five years. The clinical and pathological data were analyzed. The relationship between HOS and clinicopathological data was analyzed. Multivariate analysis was performed by logistic regression.Results: There was no clear correlation between the occurrence of HOS with sex, age, gross typing, histological grade, location of tumors, lymph node metastasis and TNM stage (p > 0.05). Preoperative complications including inflammatory bowel disease, diabetes mellitus and neoadjuvant chemoradiotherapy were risk factors for HOS (p < 0.05). Total colectomy and abdominal infection were risk factors for HOS (p < 0.05) during operation.Conclusion: Inflammatory bowel disease, diabetes mellitus and neoadjuvant radiotherapy and chemotherapy in patients with colorectal cancer are the preoperative risk factors for HOS. Total colectomy and postoperative abdominal infection are the postoperative risk factors for HOS.