Bronchodilator test is used to clarify the reversibility of airway obstruction in patients by measuring the improvement of lung function before and after medication before and after inhalation of bronchodilators. It is generally used to diagnose and differentiate diseases such as cough variant asthma, bronchial asthma, acute or chronic bronchitis, and chronic obstructive pulmonary disease. If the patient presents with wheezing, shortness of breath, coughing, rales in the larynx, etc., and the volume of gas that can be exhaled in the first second of forceful expiration is <70% of the predicted value, a bronchodilator test is required. The bronchodilator test is positive when the patient inhales a bronchodilator such as terbutaline, salbutamol, ipratropium bromide, etc., and after 20 minutes, the volume of gas that can be exhaled in the first second of forceful expiration increases by more than 12%, and the absolute value is more than 200 mL. This suggests that the patient's airway responsiveness is increased and the diagnosis of asthma can be confirmed. If the patient is diagnosed with asthma, medication is needed to control it. Inhaled glucocorticoids, bronchodilators, leukotriene receptors and other inhibitors are usually used for long-term treatment. If the diastolic test is negative, combined with pulmonary function tests suggesting obstructive or mixed ventilation dysfunction, the possibility of chronic obstructive pulmonary disease can be considered. It is recommended that the patient go to the respiratory medicine department of the hospital in time, and follow the doctor's instructions to do this test.