Purpose To explore the diagnostic value of beak sign in fetal annular pancreas by analyzing the ultrasonographic features of fetal annular pancreas.Materials and Methods The ultrasound images and clinical data of 13 cases of fetal annular pancreas diagnosed by prenatal ultrasound in Shandong Provincial Maternal and Child Health Hospital from September 2019 to December 2021 and confirmed by surgery after birth were retrospectively analyzed.The degree of duodenal stenosis at the obstruction site was observed,especially whether the angle formed by the intestinal wall could identify the fetal annular pancreas,and the ultrasonic characteristics were summarized and analyzed.Results A total of 13 fetuses with annular pancreas showed double bubble sign,3 cases showed clamp sign,and 7 cases showed beak sign at the end of duodenal dilatation.All the 13 cases underwent surgical treatment after birth,including 2 cases with duodenal atresia and 1 case with atypical intestinal malrotation.All the children had good prognosis after operation.Conclusion By observing the dilated end of duodenum and the relationship with pancreatic head,prenatal ultrasound combined with beak sign and double bubble sign could improve the diagnostic accuracy of fetal annular pancreas,which has significant value in prenatal diagnosis of fetal annular pancreas.