The main causes of hemoptysis in patients with bronchiectasis are bronchial structural changes, local small artery wall damage, and special pathogen infections, as follows: 1. Bronchial structural changes: This may lead to the subsequent expansion of local capillaries in the bronchi, causing congestion-like changes in the surrounding capillaries, and when there is inflammatory stimulation or violent coughing, it may lead to the rupture of the abnormally expanded capillary walls and cause hemoptysis. 2. Local Small artery wall damage: It may be caused by the invasion, damage or rupture of the local small artery wall, and patients with bronchiectasis with hemoptysis must be promptly treated with symptomatic treatment such as anti-infection and hemostasis. 3. Special pathogens infection: Some patients with bronchiectasis hemoptysis may also be caused by secondary special pathogens infection in the lung, such as combined tuberculosis, pulmonary aspergillosis, etc.