4D ultrasound ventricular septal defect refers to a congenital heart disease in which the abnormal development of the septal area causes left-to-right shunting of blood from the right and left ventricles. It is recommended to determine the size of the diameter of the defect opening and to formulate the next step of treatment. If the defect is small, it can be observed and may close, but if the defect is large, surgery is often required. If the defect is small, within 0.5 cm, and does not affect the hemodynamic changes of the fetus. Most of the fetuses gradually close naturally within 1 year after birth. Therefore, the fetus needs to be followed up and observed after birth to develop a specific treatment plan. If the defect opening is larger than 0.5cm, or even more than 0.8cm, the possibility of self-healing in this case is relatively small, and surgery for interventional occlusion is mostly required. If abnormalities of the fetal heart are found during the 4D ultrasound examination during pregnancy, it is recommended that targeted treatment be carried out under the guidance of the doctor.