Abstract: Objective To observe the detection effect of prenatal grade Ⅲ ultrasound on fetal congenital heart disease, and to evaluate its clinical value in screening congenital heart disease. Methods A total of 5 000 cases of pregnant women in the second trimester in Wenzhou integrated hospital of traditional Chinese and western medicine affiliated to Zhejiang university of traditional Chinese medicine were as research subjects. All subjects were examined by prenatal grade Ⅱ ultrasound detection from March 2016 to March 2019. Prenatal grade Ⅲ ultrasound detection and prenatal fetal echocardiography. All the subjects were followed up to delivery or autopsy of aborted fetuses to determine the actual incidence of fetal congenital heart disease, the sensitivity, accuracy, specificity, positive predictive value and negative predictive value of different detection techniques for fetal congenital heart disease were assessed. Results The actual incidence of congenital heart disease was 2.14%. The detection rates of prenatal grade Ⅱ ultrasound detection, prenatal grade Ⅲ ultrasound detection and prenatal fetal echocardiography were 2.46%, 1.94% and 2.02% respectively. The missed rates of prenatal grade Ⅱ ultrasound detection, prenatal grade Ⅲ ultrasound detection and prenatal fetal echocardiography were 42.06%, 11.22% and 6.54%, respectively. Kappa values of prenatal grade Ⅱ ultrasound detection, prenatal grade Ⅲ ultrasound detection and prenatal fetal echocardiography with gold standard were 0.502, 0.930 and 0.961. Conclusion The detection rate of prenatal grade Ⅲ ultrasonography for fetal congenital heart disease is high, which is consistent with the gold standard. It can effectively reduce the rate of fetal missed detection of cardiac dysplasia and is suitable for large-scale prenatal screening of fetal congenital heart disease.