Bleeding from the respiratory tract or lung tissue below the glottis and discharged through the mouth is called "hemoptysis". It can be manifested as blood in sputum or large amounts of hemoptysis. Therefore, clinically, it is often divided into small amounts of hemoptysis, moderate amounts of hemoptysis and severe hemoptysis according to the amount of hemoptysis. Severe hemoptysis usually refers to: hemoptysis of more than 100ml in one time, or hemoptysis of more than 600ml within 24 hours. It should be emphasized that the judgment of the severity of the hemoptysis patient's condition should not be overly rigid about the amount of hemoptysis, but should be combined with the patient's general condition, including nutritional status, complexion, pulse, respiration, blood pressure, and whether there is cyanosis, etc., to make a comprehensive judgment. For those who have been ill for a long time or are old and have cough and fatigue, even a small amount of hemoptysis can cause the patient to suffocate and die, so these patients should also be treated according to the treatment principles of severe hemoptysis.