Liver transplantation is an effective method for treating end-stage liver disease and metabolic diseases in children. With the advancement of surgical techniques and the improvement of perioperative management, the survival rates of patients and grafts after liver transplantation have significantly improved. However, the complication of biliary stenosis after transplantation is as high as 7.3% -33.3%, and in severe cases, it can even lead to graft failure and patient death. Therefore, the occurrence of biliary stenosis after liver transplantation seriously affects the quality of life of children, increases the economic burden on families, and urgently needs to find effective methods to reduce the occurrence of this complication. Based on the clinical practice of our center, we believe that the placement of biliary external drainage stents has the following advantages: 1 Reduce intrahepatic biliary pressure and reduce the occurrence of postoperative biliary fistula; 2. The stent has a supporting effect and can maintain the open state of the bile duct; 3. By external drainage, the quality of bile secretion by the liver can be evaluated; 4. Provide a pathway for cholangiography. However, placing external biliary drainage may also pose certain risks, including increasing surgical procedures, stent detachment causing biliary fistula, and increasing the risk of infection. This study aims to observe the effect of placing external biliary drainage stents on biliary stricture after liver transplantation in children. The aim is to evaluate the preventive effect of external biliary drainage stents on biliary intestinal anastomotic stenosis after liver transplantation in children, and to provide evidence-based evidence for reducing biliary complications in children.