Cough with purulent sputum may be caused by pneumonia, bronchiectasis, lung abscess and so on. 1. Pneumonia: Especially respiratory infections caused by bacteria, such as staphylococcus aureus and streptococcus pneumoniae, can lead to cough with purulent sputum, and sometimes sputum can be blood. 2. Bronchial dilatation: referred to as bronchial dilatation, is located in the wall of the bronchial tubes, is one of the respiratory septic diseases. Due to various pathogenic factors leading to chronic airway inflammation, increased secretions in the airway, airway contouring obstruction, sputum aggregation, airway obstruction, increasing the probability of infection, purulent sputum, manifested as coughing and coughing up purulent sputum. 3. Lung abscess: it is a suppurative lesion of lung tissue, with suppurative pneumonia in the early stage, followed by necrosis, liquefaction and abscess, manifested by high fever, cough and coughing up a large amount of purulent sputum. Cough with purulent sputum has many reasons, besides the above, it may also be tuberculosis, alveolar cell carcinoma, etc., and should go to regular hospitals in time for consultation and clear diagnosis.