Respiratory system and circulatory system diseases are the main ones. 1. Bronchial diseases: common ones are: bronchiectasis, bronchopulmonary cancer, endobronchial tuberculosis, chronic bronchitis. The rare ones are: bronchial adenoma, bronchial calculus, etc. 2.Pulmonary diseases: common ones are: tuberculosis, pneumonia, lung abscess. Rare: pulmonary bruising, pulmonary infarction, pulmonary fungal disease, pulmonary schistosomiasis, pulmonary arteriovenous fistula. 3.Circulatory system: common: mitral valve stenosis. Hemoptysis can also occur in cases of atrial septal defect and pulmonary hypertension due to arteriovenous catheterization. 4, other: blood diseases, acute infectious diseases (epidemic hemorrhagic fever), rheumatic diseases, etc.. Among them, tuberculosis accounts for 38%, bronchopulmonary cancer 9%, chronic inflammation of the lung, lung abscess 9%.