There are many reasons for occasional coughing and hemoptysis, usually related to bronchial dilatation, lung cancer, mitral stenosis and other diseases. 1. Bronchial dilatation: when the disease is serious, it will lead to damage of bronchial mucous membrane, bronchial tubes and capillaries permeability will be increased, when the mucous membrane and blood vessels of bronchial tubes rupture, it is easy to cause hemoptysis, blood in sputum and other symptoms. 2. Lung cancer: Lung tumors may have bleeding, and the blood will flow out with the trachea and bronchial tubes, which will be manifested as blood in sputum. 3. Mitral stenosis: it is one kind of cardiovascular disease, when the mitral valve is in the state of stenosis for a long time, it is easy to cause pulmonary stasis, which leads to the rupture of capillaries in the alveolar lining, and when it is serious, it will produce the rupture of bronchial veins, so it will be haemoptysis when coughing. There are many reasons for occasional coughing and hemoptysis, it is recommended that patients go to the hospital in time to identify the cause of the disease, under the guidance of the doctor for standardized treatment.