Many parents of children often ask anxiously, “Doctor, why did our child get this disease? Does it have anything to do with the flu I had during my pregnancy? Are there many children with this disease nowadays? What can we do to prevent it if we want to have another child?” In fact, the causes of congenital heart disease can be roughly divided into three aspects, such as genetic factors, environmental factors and disease drug factors. 1, genetic factors: trisomy 21 for example, the disease about 50% of patients with congenital heart disease, including endocardial cushion defect and ventricular septal defect accounted for 32% and 29% respectively, followed by atrial septal defect accounted for 11%, tetralogy of Fallot accounted for 7.9%, end ductus arteriosus accounted for 6.7%. Most of the atrial septal defect, ventricular septal defect, patent ductus arteriosus, and tetralogy of Fallot are polygenic in pattern, and the risk rate of reoccurrence of siblings and children of the first patients is about 4%. 2, environmental factors: refers to the environment in which the pregnant woman is living before and during pregnancy, including the living and working environment. Environmental factors include chemical factors and physical factors. Chemical factors are mainly long-term exposure to harmful chemicals, including benzene, sulfur dioxide and other harmful gases and heavy metals such as mercury and cadmium. Therefore, pregnant women should avoid living in newly renovated houses, as well as avoiding exposure to chemical factors and strengthening protection. Physical factors are mainly radiation, because radiation has a pathogenic effect on the human body and a teratogenic effect on the fetus. 3, disease and drug factors: According to some analysis results from medical research, drug and disease factors mainly include alcoholism of mother, aspirin of mother in early pregnancy, taking tetracycline, taking birth control pills, rubella and cold. These are all high-risk factors for congenital heart disease in children. Therefore, mothers should try to avoid drugs and disable high-risk drugs during pregnancy, especially in early pregnancy. This should be the main measure for primary prevention of congenital heart disease. The mother should also avoid colds and bacterial and viral infections such as rubella and measles in early pregnancy, because bacterial and viral infections can also lead to malformations in fetal development and cause congenital heart disease. In addition, advanced maternal age is also a high risk factor for the development of congenital heart disease in the fetus. For genetic factors, parents who have a family history of genetic diseases should try to rule out the possibility of congenital heart disease in their fetus through chromosome examination and genetic gene examination during pregnancy; in addition, to prevent the occurrence of congenital heart disease pregnant women should avoid living in newly renovated houses, avoid exposure to chemical factors; avoid exposure to radioactive substances, avoid living in an environment with strong electromagnetic waves; try to avoid using drugs, prohibit high-risk drugs.