Objective To explore the application of three-dimensional (3D) ultrasonography in screening the defects of fetal brain and skull.Methods Thirty-one cases of the fetal were detected in 3D ultrasonography.The ultrasonic data were compared with magnetic resonance imaging(MRI) and pathology.Results Among 31 cases according to 3D ultrasonography,there were 2 of anencephaly, 1 of exencephaly,2 of encephalocele,5 of holoprosencephaly,2 of arachnoidcyst, 1 of vein of Galen aneurysm,2 of agenesis of the corpus callosum, 1 of schizencephaly, 3 of Dandy-Walker syndrome, 7 of ventriculomegaly, and 5 of enlargement of cisterna magna.Compared with the results of MRI,the diagnostic accordance rate was 100% by 3D,it was 93.5% by 2D.Conclusions The structure of fetal brain and skull were viewed more clearly in 3D ultrasonography than 2D ultrasonography and the defects of fetal brain and skull can screened more exactly.