Pediatric recurrent respiratory tract infection is a common disease with complex etiology, and its clinical characteristics are recurrent respiratory tract infection with long duration, affecting the growth and development of children, and the lack of special treatment methods, which is a topic of concern for pediatricians in the current pediatric clinic. 1. Factors related to recurrent pediatric respiratory tract infections 1. Age, nutritional factors and pathogenesis Based on the special anatomical characteristics of the pediatric respiratory tract and the incomplete development of various physiological functions, the immune function is poor, the infection is easy to lead to the spread of infection and recurrent infection. Rapid growth and development of children, partiality or long-term lack of appetite, not breast-feeding or artificial feeding improper deployment, resulting in malnutrition, vitamin D deficiency disease, anemia, etc., the child’s body resistance decreased, prone to repeated respiratory infections. 2, vitamin, trace elements and calcium deficiency vitamin deficiency, especially vitamin A deficiency and the occurrence of recurrent respiratory infections in children are closely related. The level of serum vitamin A decreases in children with recurrent respiratory infections, and the reduced level is positively correlated with the severity of the disease, and the rebound is parallel to the recovery of the disease. Vitamin A supplementation may reduce the incidence of respiratory infections. Because vitamin A deficiency has an important physiological function in the differentiation and perfection of respiratory epithelial cells, deficiency impairs respiratory epithelial cells and their integrity, reduces local defenses, and predisposes to pathogenic infections. Vitamin A deficiency can also impair the function of T and B lymphocytes, making the child less resistant. Micronutrient deficiency is also an important cause of recurrent respiratory tract infections in children. Serum iron and zinc decrease significantly during the acute phase of recurrent respiratory tract infections in children, and the frequency of infection episodes is related to the degree of decrease. Zinc deficiency reduces the function of thymus and spleen or atrophy in children, and reduces the function of T cells; iron deficiency can cause dystrophic atrophic changes in pediatric respiratory epithelial cells, resulting in blocked synthesis of respiratory immunoglobulins. The interaction between trace elements in the body is important in the development of recurrent respiratory tract infections in children. Children with calcium deficiency are prone to respiratory infections and aggravate their condition. Calcium enhances the movement of tracheal and bronchial cilia, resulting in enhanced respiratory clearance, and at the same time improves the phagocytic capacity of pulmonary giant eosinophils. Therefore, proper supplementation of vitamin D to prevent vitamin D deficiency disease is important to reduce the incidence of recurrent respiratory tract infections in pediatric patients. 3, low immune function The occurrence of recurrent respiratory tract infections in children is closely related to the immune function of the body. The immaturity of specific immune function in infancy and childhood, primary or secondary immune function deficiency is an important reason for the development of recurrent pediatric respiratory infections. Children with recurrent pediatric respiratory infections have varying degrees of immunodeficiency or immature immune function. Children with recurrent pediatric respiratory infections have reduced serum IGA, IGG, defective IGG subclasses, reduced IL-_ activity, and significantly higher peripheral blood lymphocyte apoptosis rate. Therefore, improving the immune function of the body is one of the key measures to prevent and treat recurrent respiratory tract infections in children. 4, respiratory lesions and congenital diseases congenital pulmonary cyst, congenital diaphragmatic hernia, esophageal tracheal fistula, bronchial dilatation, bronchial dysplasia, tracheal foreign bodies and other diseases that make the respiratory epithelial cilia defense dysfunction, or because of the respiratory organ itself is poorly developed, dysfunctional easily lead to recurrent respiratory infections in children; in addition, congenital heart disease caused by poor pulmonary circulation, bruising can also cause recurrent respiratory infections in children In addition, gastroesophageal reflux, nephrotic syndrome and other causes of hypoproteinemia, congenital alpha_trypsin deficiency, etc. can make the incidence of recurrent respiratory tract infections in children higher. 5, infection and improper treatment Infection is the main cause of recurrent respiratory tract infections in children, respiratory infections in children are caused by viruses, common viruses are syncytial virus, influenza virus, parainfluenza virus, adenovirus, etc., bacteria have been type streptococcus, Haemophilus influenzae, Streptococcus pneumoniae and other common. Pediatric acute lower respiratory tract infections often have a mixture of _ or _ more viruses and bacteria. In addition, cytomegalovirus and Mycoplasma pneumoniae infections are not negligible in pathogenic infections in children. Clinical antibiotic abuse can lead to bacterial resistance, making treatment difficult, and the course of treatment is not sufficient, especially when the temperature returns to normal immediately stop, these situations often make the pathogenic bacteria temporarily inhibited, once the cold, overwork or resistance to decline will be re-emerging. 6, environmental and other factors Children’s passive smoking, indoor decoration, car exhaust, atmospheric pollution of the living environment, so that harmful gases inhaled into the respiratory tract, can directly affect the respiratory function of the lungs, reducing the resistance of the respiratory tract, is undoubtedly one of the causes of recurrent respiratory tract infections in children. In addition, premature birth, artificial feeding, lack of exercise, long-term use of glucocorticoids, immunosuppressants, etc. also make the incidence of recurrent respiratory tract infections in children significantly higher. Second, the correct understanding and management of recurrent pediatric respiratory tract infections Understanding the factors associated with recurrent pediatric respiratory tract infections, clinical analysis and consideration should be made from the host antibodies, pathogenic microorganisms and antimicrobial drugs, the most important of which is the organism factors, including systemic factors caused by low immunity, resistance of pathogenic bacteria to continuously developed antimicrobial drugs and irrational use. The treatment should also take into account the problem of inhibiting or killing pathogenic microorganisms by antibacterial drugs. 1, regulation of immune function to improve immunity thymidine, levamizole, transfer factor, BCG are immune enhancers, have a strong non-specific immunomodulatory function, can effectively activate the giant eosinophils and T lymphocytes, enhance the cellular immune function and regulate the level of humoral immunity, so as to significantly improve the therapeutic effect of recurrent respiratory tract infections in children, the clinical can be selectively applied. 2.Supplementation of trace elements and various vitamins Iron, zinc, vitamin A, vitamin C, vitamin B, etc. can promote the synthesis of various enzymes and proteins in the body, promote the development of lymphoid tissue, maintain the normal nutritional state and physiological function in the body, and enhance the body’s ability to resist diseases. 3, the reasonable use of antiviral drugs and antibacterial drugs Childhood repeated respiratory infections make bronchial wall structure damage, anti-microbial airway contour rate decreased, cilia purification function and local defense function is seriously reduced, so that the bacteria is difficult to be cleared and the formation of chronic foci of infection. Therefore, the rational use of antibacterial drugs is particularly important to strictly grasp the indications, application dose and method of antibacterial drug use, otherwise it will not only fail to play a therapeutic role but also lead to pathogenic bacteria to produce drug resistance or alternating flora and a variety of pathogenic microorganisms of mixed infection. Clinical practice shows that the long-term use of a large number of antibacterial drugs or a kind of antibacterial drugs are also easy to cause resistance, while the rotation of antibacterial drugs can better avoid the generation of drug resistance. Antiviral therapy can choose ribavirin, interferon, polymyxin, etc. Human alpha-interferon is effective for viral infections, and local treatment by nebulized inhalation is more effective than intramuscular injection, and should be used early. Anti-microbial treatment choose less adverse reactions ß-lactams, macrolide antibiotics, the use of principles for the selection of sensitive drugs according to the pathogenic microorganisms, sufficient amount of full course of treatment. The hormone can quickly reduce the symptoms to achieve immediate results, but can make the child’s immune function further decline, constantly leading to new infections, so that the infection and low immune function to form a vicious circle. 4.Other enhance nutrition, reasonable diet, correct unreasonable eating habits and food structure, avoid passive smoking and odor stimulation, keep indoor air fresh, arrange outdoor activities and physical exercise appropriately, and actively prevent and treat various chronic and primary diseases, such as vitamin D deficiency, malnutrition and anemia. In conclusion, the incidence of pediatric recurrent respiratory tract infections is high and the pathogenesis is complex. In addition to physiological factors, it is difficult to be explained by a single theoretical factor or doctrine, and its etiology involves many disciplines such as microbiology, immunology, molecular biology, etc. It is the result of the presence and joint action of one or more factors. Therefore, for recurrent respiratory tract infections, a comprehensive analysis and integrated treatment are necessary to achieve the expected therapeutic effect.