The immune function of children with precocious heart disease has received increasing attention in recent years, but the reported results are inconsistent, and some are even opposite. Some articles have pointed out that IgG and IgA in the blood of children with left-to-right shunt type precocious heart disease are decreased, CD4 is decreased, CD8 is increased, and CD4/CD8 ratio is decreased, suggesting that the children are both immunocompromised and immunoregulatory. The important role of secretory IgA (SIgA) in the mucosal surface of the respiratory and digestive tracts is well known. Studies have shown that although there is no direct relationship between serum IgA and SIgA, long-term observations suggest that serum IgA is inevitably deficient when SlgA is deficient, and therefore the measurement of serum IgA can reflect the level of SIgA. A study showed that the serum IgA in the preconditioned group was significantly lower than that in the control group, suggesting that this group of children has a deficiency of SIgA in the respiratory tract, and therefore cannot effectively protect the mucosa, leading to various microbial attacks, and is more prone to respiratory infections and even pneumonia than the control group of children. IgG is the main immunoglobulin that kills bacteria, neutralizes viruses and toxins, and the low IgG in the preconditioned group is consistent with our clinical observation that pneumonia in children is not easily controlled. T-cell subsets are divided into helper lymphocytes (CD4) and suppressor lymphocytes (CD8), which have the role of enhancing or suppressing the immunity of different subsets of effector T-lymphocytes and B-lymphocytes, respectively, and the relative balance of these two functionally different cells is maintained under physiological conditions. It has been shown that there is immune dysregulation and low cellular immune function in the preconditioned group, so it can be considered as another reason for the vulnerability of children with left-to-right shunt type preconditioning to infection. The significance of this immunomodulatory disorder in the development and progression of precocious heart disease needs to be elucidated after further study. The growth and development of the body tissues and organs of children with precocious heart disease are affected to a certain extent, and the low immune function is part of the systemic developmental delay. Some doctors have suggested that immunoglobulin and T-cell subsets should be routinely examined in children with left-to-right shunt type of precocious heart disease to understand their immune function and to guide clinical measures.