The symptoms of hemoptysis in patients with cavitary tuberculosis are considered to be caused by increased capillary permeability, capillary injury or ruptured aneurysm. 1. Increased capillary permeability: Cavitary tuberculosis is mainly caused by Mycobacterium tuberculosis infection, which leads to tuberculous inflammation. Tuberculous inflammation will lead to a certain degree of increase in pulmonary capillary permeability, which will lead to hemoptysis and bloody sputum. 2. Capillary damage: the lesions caused by cavitary tuberculosis will damage the small blood vessels in the patient’s lungs, which will lead to an increase in the amount of bleeding in the lungs when the patient coughs, thus resulting in hemoptysis. 3. Aneurysm rupture: if the aneurysm of the cavity wall ruptures in patients with cavernous tuberculosis, bleeding will also occur, leading to hemoptysis. Hemoptysis in patients with cavitary tuberculosis is a normal phenomenon caused by the disease, and it is recommended that the patients should consult the doctor in time and take treatment measures according to the doctor’s instructions.