Coughing up dark red blood even after the hemoptysis has stopped is usually not normal. It may be caused by respiratory system diseases, circulatory system diseases, trauma and other reasons. 1. Respiratory diseases: such as tuberculosis, lung abscess, lung cancer, bronchial stones, silicosis and other respiratory diseases. These diseases may lead to increased permeability of the bronchial mucosa or lesion capillaries, or submucosal vascular wall ulceration, thus causing coughing up dark red blood again. 2. Circulatory diseases: common rheumatic heart disease mitral stenosis, hypertensive heart disease and pulmonary arteriovenous fistula and other diseases can cause blood circulation disorders, which can lead to hemoptysis stop and then cough up dark red blood. 3. Trauma: thoracic trauma, rib fractures, blast injuries and medical operations, such as thoracic or lung puncture, biopsy, bronchoscopy, etc. can also be caused by coughing up dark red blood. In addition, systemic bleeding tendency diseases such as leukemia, hemophilia, aplastic anemia, epidemic hemorrhagic fever, disseminated intravascular coagulation, etc. may also cause this condition. It is recommended that patients with such symptoms go to the hospital in time for consultation and symptomatic treatment after clarifying the cause of the disease.