Etiology: embryo 6-7 weeks, the ventral pancreas embryonic base part failed to rotate completely to the left with the duodenum, it is like a thin narrow band around the duodenum in the descending part of the duodenum, compression of the duodenum, causing duodenal obstruction. Clinical manifestations: 1, ring pancreas is most common in infants and young children, adults are rare. 2.Part of the patients are preterm infants, and some of them have clinical symptoms after one week of birth. 3.Clinical manifestations are closely related to the degree of duodenal compression, and the degree of duodenal compression depends on the hardness of the annular pancreas or whether the compression is complete. 4. The most typical symptom is vomiting, most of which is non-bilious. Some children have chromosomal abnormalities and/or other congenital malformations, such as small bowel malrotation and esophageal atresia. Most children present with partial duodenal obstruction. 6, Some children with abdominal pain as the main symptom. X-ray: standing fluoroscopy shows “double bubble sign” in the left upper abdomen, barium meal examination of the upper gastrointestinal tract shows that the duodenum is narrowed by compression, the edge is smooth and neat, and the barium passage is obstructed. ERCP: The main pancreatic duct encircles the duodenum from the posterior lateral to the right side of the head of the pancreas and travels laterally to the left side. The main pancreatic duct is shortened at the tail of the body, and the position of the papilla is varied. 3.CT:The duodenal lumen is narrow and the wall is hypertrophied, and the duodenum can be compressed by the ring-shaped pancreatic tissue, which has the same density as the surrounding pancreatic tissue. 4.MRI:T1WI plus fat suppression image shows that the ring-shaped pancreatic tissue surrounding the duodenum is high signal, while the surrounding tissue and duodenum are low signal. 5, MRCP: The main pancreatic duct was shown to form a ring around the descending part of the duodenum, and the common duct where the pancreatic duct and the bile duct meet was very short and was located in the wall of the duodenum. 6, USG: Transverse section of the left upper abdomen of the child can see two typical liquid dark areas, showing the “double bubble sign”, which is formed by the dilatation of the upper duodenal atresia and the dilatation of the gastric bubble. On multisection examination, the two bubbles were seen to be connected to each other.