According to the following diagnostic points to determine the variant asthma: 1, the patient usually has an allergic constitution, such as a personal history of allergies and allergic diseases, such as urticaria, eczema, allergic rhinitis, etc. 2, the patient’s symptoms are usually irritating, paroxysmal dry cough, the degree of coughing is more intense, usually accompanied by a small amount of white mucous sputum, in the coughing of the severe occasional mild chest tightness, the coughing of the cough, mostly because of colds, inhalation of cold air and odors, dust, smoke and other stimuli to trigger or aggravate the original cough, the cough is mostly at night and in the morning. Because of colds, inhalation of cold air and odors, dust, fumes and other stimuli induced by the formation or aggravation of the original cough, the cough in the night and morning seizures mainly. 3, conventional antibiotics and cough suppressant drugs are not effective, the patient line bronchial excitation test and expiratory fluid nitric oxide measurement was a positive reaction, the patient in the use of inhalation glucocorticosteroids and bronchodilator can be used to alleviate the cough, then the diagnosis can be confirmed, and the cough can be diagnosed with a severe, paroxysmal dry cough. If the cough is relieved by inhaled glucocorticoids and bronchodilators, the diagnosis of cough variant asthma is confirmed.