To investigate the prenatal ultrasound diagnosis (B ultrasound) sonographic characteristics of fetal congenital malformations，and provide information forclinical，timely termination of pregnancy for fetal malformation，the production of pregnant womenby ultrasonography，routine obstetric fetal system，measurement，observation of fetal malformation. 42 cases of fetal malformation，2 cases were missed diagnosis.conclusion. Fetal ultrasonography has important clinical value in diagnosis of malformation.