The common causes of coughing and bleeding are as follows: 1. Inflammation: upper respiratory tract infection causes damage to the mucous membrane of the throat, which leads to capillary rupture when coughing and causes a small amount of blood sputum. In addition, violent coughing caused by bronchitis can also appear blood sputum, among which chronic bronchitis can produce a whole mouth of blood sputum, but usually does not exceed 10-20 ml; 2. tuberculosis: repeatedly coughing blood sputum, with the duration of the disease exceeding 1-2 months; 3. bronchiectasis: the duration of the disease is longer, but the patient’s general condition is better, and CT examination can confirm the diagnosis; 4. lung cancer: it is manifested by repeatedly coughing blood in small amounts within a short period of time, and the amount of blood coughing rarely exceeds 100 ml. Diagnosis can be helped by X-ray and CT examination; 5. Other causes: such as blood disorders, bronchial vascular malformation, pulmonary embolism, such as pulmonary embolism manifested as sudden hemoptysis, chest pain and difficulty in breathing.