Pulmonary function tests can have four reported results: normal, restrictive ventilation dysfunction, obstructive ventilation dysfunction, and mixed ventilation dysfunction. It is only one kind of functional test, not disease specific, but bronchial asthma is mainly seen in obstructive ventilation dysfunction. Chronic obstructive pulmonary disease, emphysema are prone to restrictive dysfunction and mixed dysfunction, and normal people mainly belong to normal lung function. Patients with chronic bronchitis, emphysema, bronchial asthma, and even with heart failure and respiratory failure can develop mixed ventilation dysfunction. Therefore, obstructive ventilatory dysfunction is not asthma, but only suggests changes in lung function, but also depends specifically on the lesions in the large and small airways and clinical manifestations. For example, if there is a family history of genetic predisposition, allergic rhinitis, positive allergen tests, or the onset of asthma in young people, the clinical and ancillary tests are combined to determine whether it is an asthma attack.