Twelve cases of abnormal abdominal walls in fetuses are reported in this paper. Among them, there were 4 cases of umbilical hernia, 4 cases of a defective abdominal wall, 3 cases of diaphragmatic hernia and 1 case of a defective thoracic and abdominal wall. From the features of the sonographic picture, the reasons for misdiagnosis are discussed. From our analysis, the main points of differential diagnosis and the earliest time for making diagnosis are proposed. The diagnostic rate could be improved obviously by systemic and careful examination which is important for deciding the model and time of deliveries.