Pediatric congenital bile duct dilatation is the most common type of congenital biliary malformation in clinical practice. It is a congenital malformation in which a portion of the common bile duct is cystically or spindly dilated, sometimes accompanied by dilated intrahepatic bile ducts. The incidence is higher in women than in men, accounting for about 60% to 80% of the total incidence. In addition to cystic dilatation of the common bile duct, about half of the patients show only cystic or cylindrical dilatation of the common bile duct, and about 1/4 of the cases also have a combination of dilatation of the intrahepatic bile duct. Caroli’s disease is considered if only dilated intrahepatic bile ducts are present, and liver transplantation is required in the distant future. Children often present to the hospital with one or more of the 3 classic symptoms of abdominal pain, jaundice and abdominal mass. The diagnosis of the disease is relatively easy, with a high diagnostic accuracy by ultrasound and MRCP. Because of the recent effects on liver function and the possibility of bile duct cancer in the long term, once the diagnosis is made, elective surgery is required. In the past, open choledochal cystectomy + common hepatic duct jejunojejunal ROUXY anastomosis was mostly used for this disease, but in the past 10 years, with the development of laparoscopic technology, laparoscopic surgery has been adopted in large pediatric medical centers, but this laparoscopic surgery is an advanced surgery in the field of pediatric general surgery, which is a “test” for doctors and requires more experience in open and laparoscopic surgery. However, this laparoscopic procedure is an advanced procedure in the field of pediatric general surgery and is a “test” for the surgeon, requiring extensive experience in both open and laparoscopic surgery to perform. But the hard work does pay off, as we have repeatedly shown that the child has an aesthetically pleasing postoperative wound, quick recovery, and less chance of long-term intra-abdominal complications! We are posting a case of a 16x11x9cm common bile duct cyst with a wall thickness of nearly 1cm, which was quite difficult to operate on.