The prevalence of chronic cough in children in China is about 6,4%. Since cough is only a symptom, many parents are used to giving their children self-purchased OTC drugs based on experience, and doctors often neglect cough symptoms or stay on symptomatic treatment, acute cough <3 weeks, subacute cough 3-8 weeks, chronic cough ≥8 weeks, pediatricians refer to >4 weeks as chronic cough, definition of chronic cough cough >8 weeks ( Pediatrics >4 weeks), cough is the only or main symptom, no hemoptysis, sputum or no sputum, and no history of recurrent respiratory infectious diseases. Chronic cough etiology diagnosis flow chart Specific steps: 1. History and physical examination Narrow the diagnosis by history questioning. 2.Radiological examination Routine X-ray chest films can be selected for further examination according to their morphological nature if lesions are present. Chest CT: small and medium-sized lesions in mediastinum, hilar lymph nodes and lung fields, high-resolution CT: atypical branched dilatation, interstitial lung lesions, etc. 3, Those with no obvious lesions on chest X-ray, such as passive smoking and environmental irritants, are removed from exposure to irritants. 4.If the cough remains unrelieved or without the above-mentioned triggers, proceed to the next diagnostic procedure. Lung ventilation function + bronchial excitation test to diagnose and identify CVA; normal ventilation function and negative excitation test, induced sputum examination to diagnose EB; in the presence of postnasal drip or frequent throat clearing, treatment can be started according to UACS; combined use of first-generation H1 receptor blockers and nasal decongestants; for allergic rhinitis, nasal inhalation glucocorticoids can be added; if symptoms do not improve after 1 to 2 weeks of treatment, take Sinus CT or nasopharyngoscopy. If the above tests are not abnormal, or if the patient has reflux-related symptoms, 24-h esophageal pH monitoring may be considered – GER, and if pH monitoring is not available, empirical treatment – anti-reflux therapy may be administered if there is a high degree of suspicion, and if AC is suspected, allergen skin testing, serum IgE and cough sensitivity testing are feasible. High resolution CT; fibrinoscopy and cardiac examination should be considered. Exclude external bronchial dilatation, airway malformations, foreign bodies, endobronchial tuberculosis and left heart insufficiency. Other: PPD skin test, serum total IgE and specific IgE assay, skin prick test, 24-hour esophageal pH monitoring, esophageal intraluminal impedance testing, etc. The diagnostic value of exhaled air NO measurement, tracheobronchial biopsy, and cough receptor sensitivity testing for chronic cough in children is uncertain. The etiological diagnosis can be established only after the cough is relieved with appropriate treatment. Some patients may have multiple etiologies at the same time, and if the patient has partial relief of cough symptoms after treatment, consideration should be given to whether other etiologies are combined at the same time. The etiological diagnosis of chronic cough should be based on the following principles: emphasis on the medical history, including the history of the five senses and digestive system; selection of relevant tests according to the medical history, from simple to complex; examination of common diseases first, followed by rare diseases; diagnosis and treatment should be carried out simultaneously or sequentially; if conditions are not available, diagnostic treatment should be based on clinical features, and the cause of cough should be determined according to the response to treatment; relevant tests should be selected when treatment is ineffective; in the absence of a clear In the absence of a clear indication of the cause, diagnostic treatment should be carried out in the order of UACS, CVA and GERC. The clinical diagnosis of chronic cough mainly relies on the history, symptoms, signs and positive findings of ancillary tests. The etiological diagnosis can only be established after specific examination and treatment for a certain etiology and disappearance or significant reduction of cough symptoms.