Double bubble sign is a manifestation of duodenal obstruction. There are many causes of double bubble sign, such as seen in duodenal atresia, loop pancreas, intestinal malrotation and other diseases. 1. Duodenal atresia: It is a congenital developmental defect that can be caused by injury to a part of the intestinal canal, among other factors. Prenatal manifestations include excessive amniotic fluid, marked dilatation of the stomach and duodenal bulb, etc. The child may suffer from dehydration and aspiration pneumonia. 2. Circumscribed pancreas: abnormal development of pancreatic tissue in the form of rings or bands, a congenital developmental defect, can be caused by hyperplasia and hypertrophy of pancreatic primordium, abnormal development of pancreatic primordium during embryonic period and other factors. Prenatal dilatation of the stomach and duodenum bulb, double bubble sign and other symptoms can be seen, and after birth, the child may be accompanied by bilious vomiting and other symptoms. 3. Intestinal malrotation: it is a kind of congenital malformation that can cause duodenal obstruction and small intestinal torsion, which can be caused by factors such as intestinal positional variation and mesenteric attachment incompleteness. The main manifestations are vomiting, high intestinal obstruction, and bilious vomiting in the child. If the double bubble sign is detected, the child should go to the hospital immediately for further relevant examinations to clarify the disease and its progress, and actively cooperate with the doctor’s treatment.