Possible reasons for coughing up sputum with blood include bronchitis, bronchiectasis, pneumonia, tuberculosis, lung abscess, pulmonary hypertension, lung cancer and other respiratory diseases, in addition, acute left heart failure may also lead to coughing up sputum with blood, gastrointestinal bleeding can also occur when coughing up sputum with blood. 1. Acute and chronic bronchitis, tracheal mucosal congestion and edema, increased airway secretions, damage to the epithelial cells, blood vessel wall, sputum with blood. 2. In bronchiectasis, the bronchial wall is thickened and structural changes occur. The thickened wall of the bronchial tubes may pull on blood vessels, resulting in coughing and sputum with blood. 3. Pneumonia may be the result of infection of the lung parenchyma by bacteria and fungi, leading to lung liquefaction and necrosis. 4. Tuberculosis bacillus involves the lung parenchyma, leading to lung liquefaction, necrosis, etc. Severe infection of the lungs leads to abscess cavities in the lung parenchyma, which may lead to coughing up sputum with blood when the blood vessels are involved in the above lesions. When pulmonary arterial hypertension obstructs pulmonary circulation, the pressure of pulmonary blood vessels is too high, which may lead to pulmonary stasis, pink foamy sputum, coughing up sputum with blood, and so on. 5. Tumor cells invading small blood vessels in lung cancer may lead to coughing up sputum with blood. 6. Acute left heart failure leads to pulmonary vascular stasis, resulting in increased capillary exudation and coughing up sputum with blood. 7. Peptic ulcer and other causes of gastrointestinal bleeding, mixed with phlegm may be manifested as coughing up sputum with blood. There are many other reasons for coughing up sputum with blood, such as bleeding in the upper respiratory tract, backflow into the respiratory tract with sputum coughed up, there will also be blood in the sputum, it is recommended to consult the hospital to identify the cause of the disease, and standardized treatment.