Chronic cough in children is a condition with cough as the only or main clinical manifestation, with a duration of more than 4 weeks and no significant abnormalities on chest radiographs. Its diagnosis should take full account of age factors, with procedures ranging from simple to complex and from common to rare diseases, with emphasis on age as a hint to the possible etiology of chronic cough in children, and the prevalent phase of cough caused by each etiology within 24 hours. Diagnostic treatment is helpful in the diagnosis of chronic cough in children as follows: 1. In the absence of clear etiologic hints, diagnostic treatment is performed in the order of cough variant asthma, upper airway cough syndrome and post-infectious cough, including history taking, age, duration of cough, nature of cough, presence of snoring, history of foreign body or suspected foreign body inhalation, and history of medication taking, previous history of wheezing, history of allergic diseases Physical examination includes growth and development, respiratory rate, thoracic deformity, tonsillar or proliferative hypertrophy and enlargement, follicular hyperplasia and secretion adhesion in the posterior pharyngeal wall, cyanosis and pestle finger, etc. Particular attention should be paid to lung and heart examination. 3. bronchoscopy, etc.; 4. Allergen testing, such as 24-hour lower esophageal pH test and exhaled breath nitric oxide measurement. Chronic cough in children is determined by these results to clarify the cause, provide symptomatic treatment, and verify the correct diagnosis by the treatment effect.