Duodenal membranous stenosis is a common type of congenital duodenal obstruction. The conventional diagnosis method is abdominal x-ray plain film and upper gastrointestinal series. These examinations have high accuracy, but they are limited by radiation. In application, ultrasound has the advantages of non-radiation and repeated dynamic observation. Recently, ultrasound has been widely used in the diagnosis of congenital duodenal obstruction. In this case, the milk-assisted contrast-enhanced gastrointestinal ultrasound examination is more effective than conventional ultrasound. Excellent examination, the anatomical structure can be displayed more clearly through the contrast acoustic window of milk. This examination method combined with other imaging examinations can provide clinicians with more valuable diagnostic information, which is worthy of further promotion and application.