1. Recurrent episodes of wheezing, shortness of breath, chest tightness, or cough are mostly associated with exposure to allergens, cold air, physical or chemical irritation, viral upper respiratory tract infections, and exercise. 2.Disseminated or diffuse, expiratory phase dominated croup with prolonged expiratory phase can be heard in the lungs during the attack. 3. The above symptoms may be relieved by treatment or may resolve on their own. 4.Except wheezing, shortness of breath, chest tightness and cough caused by other diseases. 5, Those with atypical clinical manifestations (such as no obvious wheezing or signs) should have at least one of the following Positive bronchial excitation test or exercise test, positive bronchial diastolic test (FEV1 increase ≥ 12% and absolute FEV1 increase ≥ 200 ml), peak expiratory flow rate (PEF) intra-day (or 2 weeks) variability ≥ 20%. Those who meet items 1-4 or 4+5 can be diagnosed with bronchial asthma. Those with typical signs and symptoms can be directly diagnosed as asthma, while those with atypical signs and symptoms need to have pulmonary function tests.