To analyze the clinical effect of ultrasound combined with chromosomal examination for diagnosing the fetal cardiac malformations. Methods: 339 pregnant women with high-risk factors who diagnosed in hospital between January 2020 and May 2023 were taken as the study subjects, and the fetal cardiac development of these women were analyzed by the cardiac ultrasound and chromosome examination. The fetal cardiac abnormality was diagnosed by the abnormal result of the cardiac ultrasound or the chromosomal examination. The pregnant women and their fetuses were followed up and their prognosis was recorded. The results of the fetuses with defects by autopsy and by postnatal findings were used as the gold standard for diagnosing the fetal cardiac malformations in this study. Results: 339 high-risk pregnant women were examined by the fetal cardiac ultrasound, and there were 111 (32.7%) cases with fetal cardiac abnormalities. The top three fetal cardiac abnormalities were ventricular septal defect (9.7%), persistent left superior vena cava (7.1%) and aberrant right subclavian artery (5.3%). The number and structure of fetal chromosomes in 339 women were examined by amniocentesis and 36 (10.6%) fetuses with abnormal chromosome number or structure, including 32 (9.4%) cases with abnormal number and 4 (1.2%) cases with abnormal structure. The most common chromosome abnormalities were trisomy 21, trisomy 13 and trisomy 18. Among 111 cases with fetal cardiac malformation diagnosed by ultrasound, 28 fetuses had abnormal chromosome. Among 228 fetuses with normal cardiac development by ultrasound, 8 fetuses had chromosomal abnormalities (P<0.05). Based on those of the gold standard, the sensitivity and the specificity of the ultrasound for diagnosing the fetal cardiac abnormalities were 77.8% and 72.6%, and which of the chromosome examination were 25.2% and 96.5%. The sensitivity and the specificity of the combined detections of the ultrasound and the chromosome examination for diagnosing the fetal cardiac abnormalities were 93.1% and 97.3%. The combined detections of the ultrasound and the chromosome examination for the fetal cardiac abnormalities had higher diagnostic value. Conclusion: The combined detections of the ultrasound and the chromosome examination for diagnosing the fetal cardiac abnormalities has higher sensitivity and specificity, which has higher clinical application value.