BACKGROUND Endoscopic biliary stent implantation is a recognized and effective method for the treatment of benign and malignant diseases of the bile duct and pancreas, ensuring smooth bile drainage. Currently, stent migration is considered a long-term and complex process, and in most cases, stents are removed through endoscopy or expelled from the body through the intestinal cavity. In rare cases, stents lead to formation of duodenocolic fistulas. CASE REPORT We report a case of duodenal colon fistula caused by a biliary stent penetrating the duodenum and entering the ascending colon. We removed the stent through endoscopy and clamped the fistulas of the colon and duodenum separately with titanium clips. Due to the presence of large common bile duct stones, nasobiliary drainage was performed again. Later, laparoscopic choledocholithotomy was performed, and the patient was discharged after rehabilitation. CONCLUSIONS ERCP endoscopy must consider the possibility of stent displacement in patients with biliary stents. In the case of CBD biliary stent dislocation in the patient, continuous abdominal plain films and physical examinations are required until spontaneous discharge is confirmed. In addition, for patients with benign bile duct stenosis undergoing biliary drainage, doctors should urge them to return to the hospital on time to remove the stent. For patients with postoperative abdominal pain or peritonitis symptoms, abdominal CT scan confirmation is required and early intervention should be considered.