Objective. To explore the diagnostic value of abdominal B-ultrasound in the diagnosis of congenital heart disease complicated with extracardiac malformations in the second trimester of pregnancy. Methods. 50 pregnant women with congenital cardiac malformations and extracardiac malformations diagnosed in our hospital from 2015 to 2019 were retrospectively analyzed. The diagnostic results and the types of congenital heart disease complicated with extracardiac malformations were compared to analyze the diagnostic value of abdominal B-ultrasound. Results. In the diagnosis of 50 fetuses with congenital heart disease and extracardiac malformation, the tetralogy of Fallot syndrome accounts for the largest proportion. Abdominal B-ultrasound in the second trimester was associated with a higher detection rate of fetal heart malformation (72%) versus in the third trimester (40%) ( P < 0.05 ). The single atrium and single ventricle had the highest diagnostic accuracy of fetal congenital heart malformation in the second trimester. The highest success rate of detection at different gestational weeks was observed at the 14th gestational week ( P < 0.05 ). Four-chamber cardiac section (4CV) had the lowest diagnostic accuracy (62%) for cardiac malformations, and the 4CV + three-vessel-trachea plane (3VVT) had the highest diagnostic accuracy (90%) for cardiac malformations. Conclusion. Abdominal B-ultrasound features a high diagnostic value for congenital heart disease complicated with extracardiac malformations in the second trimester of pregnancy, and the second trimester is the optimal detection timing with the highest detection accuracy.