Coughing up black bloody sputum, analyzing its possible causes are as follows: First, pneumonia, often acute onset, can be accompanied by fever, chest pain and other related symptoms, blood routine and chest CT examination can be clearly diagnosed. Second, bronchiectasis, patients often manifested as repeated coughing, coughing up sputum or accompanied by hemoptysis, if the diagnosis of bronchiectasis is clear, it is necessary to do chest HRCT examination. Third, tuberculosis, often manifested as afternoon low fever, night sweats, weight loss, the onset of the disease is relatively insidious, sputum antacid staining positive can be clearly diagnosed. Lung cancer, for patients over 40 years old, long-term smoking, especially those with family history of lung cancer, should be highly suspected of lung cancer, the diagnosis of lung cancer requires chest CT and bronchoscopy, and even lung puncture biopsy for further clarification.