Ventricular septal defect is the most common congenital heart disease and is not usually a complex congenital heart disease, but sometimes it is more serious, depending on the size of the defect, which is very large and may be combined with pneumonia, heart failure and other diseases. It is possible for a ventricular septal defect to heal itself, and it is more likely to heal itself in children within one year of age, according to statistics, about 90% of them occur within one year of age. If the defect is still moderately small after one year of age, it is recommended to find a suitable time for surgery between one and three years of age; if the defect is still very large after one year of age and affects the growth and development, it is recommended to operate as soon as possible. Regarding the indications for surgery the first thing is to look at objective indicators: the amount of quantitative defect. In general, the echocardiogram of the heart measures the objective value, but this qualitative alone is not enough. The decision to operate must be quantitative, i.e., what is the size of the defect. For newborns or small infants, if it is larger than 6 mm, early surgery is recommended, because a defect of 6 mm or more can cause lung congestion, which can very easily lead to pneumonia and even heart failure, which can endanger the life of the child. If the defect is less than 3 mm, parents can continue to observe and wait, as it may heal on its own. If the defect is 4~5 mm, it is recommended to have a close follow up first, with ultrasound every three months to see if there is any change. The next thing is to look at the symptoms: look at whether they eat milk, whether their appetite is good, and whether their weight is normal. A normal child grows about 2~3 pounds a month, if the affected child only grows 500 grams a month, it is obviously a growth retardation. Because the ventricular septal defect is too large, the body cannot absorb nutrients, so it shows no weight gain and poor appetite. Second, it depends on whether the child often suffers from colds, which in turn causes bronchitis and pneumonia. If the defect reaches more than 5 or 6 mm, poor milk intake, weight gain, growth restriction, frequent colds and even pneumonia, surgery must be done as soon as possible.