Fetal heart ultrasound can dynamically observe the internal structure of the heart and understand the function of the fetal heart, usually it is better to do fetal heart ultrasound at 24-28 weeks. As there are some individual differences in fetal development, the most suitable time for fetal heart ultrasound should be advised by the medical professionals in the light of the actual clinical situation. In early pregnancy, due to the imperfect development of the fetus, it is easy to show certain lesions; while in late pregnancy, the fetus is larger, the amniotic fluid volume is relatively reduced, and the restriction of fetal activities will affect the results of the examination. When the fetus is 24 to 28 weeks, the heart ultrasound image will be clearer, so the fetal heart ultrasound is usually the most appropriate at 24 to 28 weeks of pregnancy. Because the development of the fetus may be different from the actual situation, the most suitable time to do fetal ultrasound should be decided by the professional physician in conjunction with the development of the fetus to determine the specific appropriate time for the examination. Fetal heart ultrasound is a non-invasive test that can determine whether the fetus has congenital heart disease, and is of great value for early screening of the fetus, such as timely detection of dysplasia or atresia and other diseases. It is recommended that pregnant women should have fetal heart ultrasound at the appropriate gestational weeks under the guidance of a doctor to detect fetal abnormalities in time and take timely and appropriate treatment measures.