The causes of postoperative abdominal pain after choledochal cyst surgery include postoperative reaction, as well as the effects of some diseases such as gastric emptying obstruction, bile-intestinal anastomotic fistula and so on. 1. Postoperative reaction: In the process of choledochal cyst surgery, the surgical incision as well as the damage to some tissues and organs during the surgery will lead to abdominal pain after surgery, which is a normal postoperative phenomenon. As the condition improves, the patient’s symptoms can be gradually reduced. 2. Gastric emptying disorder: Functional gastric emptying disorder is a common complication after gastrointestinal surgery, and biliary surgery may also affect gastric function. Mental tension, activation of the inhibitory sympathetic reflex system during surgery, and stress of the body can all lead to gastric emptying disorder. Patients may present with abdominal pain and distension, nausea and vomiting. 3. Biliary-intestinal anastomotic fistula: biliary-intestinal anastomotic fistula is one of the common complications during surgery, and the fluid flowing out of the anastomotic fistula will cause abdominal pain in patients. 4. Cholangitis: Because the normal structure of the bile ducts has been changed, the bile ducts are more susceptible to bacterial infection, which can cause cholangitis and lead to abdominal pain. When patients experience discomfort, they should go to the hospital immediately.