The symptoms of asthma are recurrent wheezing, dyspnea, chest tightness or cough, which are mostly related to contact with allergens, cold air, physical and chemical stimuli, viral upper respiratory tract infection and exercise. The causes of asthma are as follows: First, it is caused by infection. Infection is the most common cause of bronchiectasis, such as chronic bronchitis, bronchial pneumonia after measles and whooping cough, tuberculosis and so on. Second, bronchial obstruction. There are tumors, swollen lymph node compression and bronchial inhalation of foreign bodies, which can cause bronchial incomplete obstruction. Third, a few are related to congenital hypoplasia. Regarding the cause of asthma, we should go to a regular hospital for examination in time. If it is diagnosed, we need to evaluate the severity and make a long-term treatment plan.