The methods to determine whether a child has asthma are as follows: 1. symptoms: most children show symptoms such as recurrent wheezing, cough, shortness of breath and chest tightness, and they usually appear at night, in the early morning or after exercise; 2. signs: they show more diffuse croup in both lungs, and the expiratory phase is predominant, and sometimes prolonged expiration can occur; 3. anti-asthma treatment is effective; 4. other diseases causing wheezing, cough, shortness of breath and chest tightness can be ruled out through ancillary examinations; 5. relevant lung function index tests, such as the first second expiratory rate and peak flow rate values, are performed to determine whether there is reversible expiratory airflow restriction.