Tetralogy of Fallot is the most common cyanotic congenital heart disease in childhood, consisting of four defects: ventricular septal defect, obstruction of the right ventricular outflow tract, overriding aorta, and right ventricular hypertrophy. It is a type of congenital heart disease, which generally stems from abnormal cardiovascular development during fetal life, resulting in cardiovascular malformations not controlled by chromosomes. The malformation of the cardiovascular system is mainly caused by genetic factors, environmental factors, and their interactions. The exact cause of this congenital heart disease has not been fully identified yet, indicating that it is not a chromosomal disease but a result of cardiovascular developmental abnormalities during fetal life.