At present, 2D ultrasound examination remains the basis of fetal diagnosis for many reasons. However, in the specific setting of sonographic evaluation of the fetal CNS, 3D imaging is helpful in diagnosis of CNS anomalies in that it allows acquisition of scanning planes along different directions. In this study, 3D ultrasound was used for diagnosis of fetal CNS congenital anomalies in 40 cases. By the 2D ultrasound, 20 cases were already diagnosed with apparent CNS anomalies and the remaining 20 cases were with no apparent fetal CNS congenital anomalies. 3D ultrasound proved to have many advantages over 2D ultrasound in the diagnosis of fetal congenital CNS anomalies.