Objective To investigate the application of prenatal ultrasonograpy in diagnosis of fetal heart disease during the medium-term and terminal pregnancy,and to avoid misdiagnosis.Methods The prenatal ultrasonographic screening was conducted in 7020 pregnant women with medium-term and terminal pregnancy.All confirmed and suspicious cases of fetal heart disease were observed by echocardiography once 4 weeks until postnatal sixth month to 1 year while normal cases was traced at the intervals of 8 weeks.All the cases were confirmed by autopsy or surgery while part of them were confirmed by postnatal angiocardiography before surgery.The reasons of misdiagnosis were analyzed.Results In fifty-three cases of fetal cardiovascular abnormality,43 cases were found,2 cases were misdiagnosis while 8 cases were missed diagnosis.2 cases of misdiagnosis included 1 case of pulmonary valve stenosis and 1 case of tetralogy of Fallot.8 cases of miss diagnosis included 2 cases of inferior vena cava in ectopic drainage and 6 cases of ventricular septal defect (defect diameter ＜ 5 mm).The accuracy rate of diagnosis of fetal heart disease was 81.1 ％ by echocardiography.Conclusions Using high frequency probe,image zoom,enhancing the detection of vein-atrium connection and the structure of right ventricular outflow with pulmonary artery are important factors to avoid missed diagnosis and incomplete diagnosis.