Dense shadows on the lower wall of the left main bronchus may be caused by bronchial phlegm embolism, foreign bodies, calcified foci, and tumors, etc. They can be treated with medications, such as Ambroxol Hydrochloride solution, or with surgery. 1. Bronchial phlegm embolism: If it is caused by pneumonia or other causes of bronchial phlegm embolism, you need to take anti-inflammatory phlegm medication under the guidance of a doctor, such as amoxicillin, aminoglutethimide hydrochloride solution and so on. 2. Foreign body: it may be the inhalation of rounded food such as soybean and soybean into the airway, forming a foreign body in the airway. It is recommended that the patient go to a regular hospital and have the foreign body removed by a doctor under bronchoscopy. 3. Calcified foci: High-density shadow should also pay attention to calcified foci, such as lymph node tuberculosis, lymph node calcification or stones. It is recommended to have regular checkups according to the doctor’s advice. 4. Tumor: it may be caused by tumor due to chemical, physical, biological, genetic and other factors, and it is recommended that the patient adopts surgery-based comprehensive treatment. As the causes of hyperdense shadow on the lower wall of the left main bronchus are different, the treatments will also be different, so it is recommended that patients go to regular hospitals in time and follow the doctor’s instructions for examination and treatment.