Phlegm in the trachea can be caused by respiratory infections, smoking, chronic obstructive pulmonary disease, lung cancer and other diseases, and targeted treatment can be given according to the cause of the disease. 1. Respiratory infections: upper respiratory tract infections, bronchitis, pneumonia and other diseases can cause sputum in the trachea. Symptomatic treatments can be taken to resolve sputum, such as taking drugs such as aminoglutethimide, bromhexine, etc., and acetylcysteine nebulization therapy can be given when necessary. If there is a basis for bacterial infection, need to actively anti-infection treatment, can use amoxicillin, levofloxacin and other drugs. 2. Smoking patients: especially long-term daily smoking a large number of people, may appear in the airways with the symptoms of phlegm, need to quit smoking in time in order to alleviate the symptoms. 3. Chronic Obstructive Pulmonary Disease (COPD): It is mainly characterized by chronic cough, sputum and shortness of breath after activity. If the amount of sputum is large and not easy to cough up, acetylcysteine can be used to dissolve the sticky sputum and promote its discharge. Anticholinergics such as tiotropium bromide can be used to control the condition in the long term. 4. Lung cancer: Lung cancer can also have symptoms such as coughing, coughing up sputum and blood in sputum, etc. According to the stage of lung cancer and gene mutation, surgery, radiotherapy, chemotherapy and targeted therapy can be given. There are also other diseases that can cause phlegm in the airway. If the symptoms do not ease or worsen, it is recommended to consult the doctor in time, improve the examination, clarify the cause of the disease and follow the doctor’s instruction for treatment.