Background:Congenital diaphragmatic hernia(CDH) is an embryonic stage in which the abdominal organs enter the thoracic cavity under the action of pressure difference between the thoracic and abdominal cavity, resulting in pulmonary hypoplasia due to the dysplasia of the diaphragm and the failure to heal the posterolateral pleura and peritoneum during the development of the diaphragm.Case presentation: A 7-month-old girl was admitted to hospital with the chief complaint of repeated vomiting for 1 day. Diagnosis was established by chest and abdominal radiographs and computerized tomography(CT). During the operation, it was found that there were many contents of intrathoracic hernia, and the hernia sac orifice was small. It was difficult to return them by thoracoscopy,then they were transferred to laparoscopic-assisted content return of diaphragmatic hernia.The patient had a good postoperative result.Conclusion: This is a very rare case of Congenital diaphragmatic hernia with small hernia sac orifice, and it emphasizes the significance of preoperative computerized tomography.