Infants and children have poor defenses and immature lung development, so they have the highest incidence within 2 years of age, mostly secondary to upper respiratory tract infections and acute infectious diseases, and are most common in winter and spring. What should be checked for chronic cough, sputum and wheezing in winter and spring? 1. Increased airway reactivity, mostly mild – moderate. The test procedure may induce an irritating cough similar to that at the onset of the disease. 2. Lung function impairment is between normal and typical asthma. 3, Skin allergen test may be positive. 4.Serum IgE level is increased. 5.Bronchodilator test may be positive in some patients. When there is a positive reaction, it indicates the presence of certain spasm and obstructive state of airway. 6. Increased peripheral blood eosinophil counts and increased serum ECP levels. Pay attention to the medical history, including the history of medication, otorhinolaryngological and digestive system examination; select relevant tests according to the medical history, from simple to complex; common diseases first, then rare diseases; diagnosis and treatment should be synchronized or sequential; when conditions are not available, diagnostic treatment should be based on clinical features and morbidity ratio; partly effective consideration of the multiplicity of cough etiology.