Congenital heart disease is the leading cause of fetal death, with a mortality rate of about 6 per 1,000. Accurate prenatal diagnosis can improve the prognosis of infants, especially important in cases of catheter-dependent congenital heart disease. Fetal echocardiography is considered to be one of the most important tests for prenatal evaluation of fetal cardiovascular malformations, and we are the first in the province to carry out fetal echocardiography. What is fetal echocardiography? Fetal echocardiography is a technique that uses modern electronic technology and ultrasound principles to examine the fetal heart, which is non-invasive, painless and reproducible to the fetus, and can observe the structure of the heart chambers, the thickness of the heart muscle, the morphology and activity of the valves as well as the function of the heart. Fetal echocardiography is one of the fourth level of targeted ultrasound for prenatal testing. Which expectant mothers need a fetal echocardiogram? Generally, fetal echocardiography should be performed if high risk factors for congenital heart disease are identified in low-risk groups. Fetal risk factors for congenital heart disease include both maternal and fetal risk factors. Although fetal echocardiography is a comprehensive evaluation of the structure and function of the fetal heart, it is not able to detect all fetal congenital heart disease because the fetus is affected by a variety of factors such as the thickness of the abdominal wall of the pregnant woman, the amount of amniotic fluid, and the position of the fetus in the uterus, and it can only detect about 70-80% of congenital heart disease, and it is easy to miss the diagnosis of atrial septal defect, small ventricular septal defect, and extracardiac vascular anomaly, etc. In addition, there are some congenital heart disease that can only be diagnosed by maternal side and fetal side. In addition, some congenital heart disease only appears in the late pregnancy, and in the late pregnancy due to the influence of fetal bone calcification acoustic shadow, as well as such as maternal obesity or fetal prone position and other reasons, making the comprehensive examination of the fetal heart has become very difficult, which also caused some difficulties in detecting some of the congenital heart disease of the fetus.