Coughing up sputum with blood is often seen in bronchiectasis, tuberculosis, bronchopulmonary cancer, mitral stenosis and other diseases, should consult a doctor in time to clarify the diagnosis. 1. Bronchiectasis: when coughing stimulated by inflammation, blood vessels rupture with sputum, i.e. sputum with blood; patients with bronchiectasis and tortuous bronchial tubes accompanied by small arteries may be dilated or angiomatous changes, when inflammation attacks the vessel wall, small arterial rupture may occur, which may cause hemoptysis. 2. Tuberculosis: hemoptysis is caused when the cavity of tuberculosis is formed and the necrosis of the cavity wall erodes the blood vessels, about 1/3 of the patients have hemoptysis, and most of them have a small amount of hemoptysis, i.e., blood in sputum. 3. Bronchopulmonary cancer: blood in sputum can be caused when cancerous tissue invades bronchial artery and vein. 4. Mitral stenosis: mitral stenosis leads to increased pressure of heart, which causes increased pressure of pulmonary vein and rupture and bleeding. In addition to the above mentioned diseases, lung abscess, pulmonary hemorrhagic nephritis syndrome and so on can also cause blood in sputum. When patients have blood in sputum, they should go to regular hospitals in time to do relevant examinations to make a clear diagnosis, and then take corresponding treatments according to the diagnosis.