Coughing up green sputum indicates the possible presence of Pseudomonas aeruginosa infection, which requires sputum culture to clarify the pathogen of the infection inside the sputum, as well as blood tests and lung CT to clarify whether there is any infection or structural damage in the lungs, such as pneumonia, bronchiectasis, chronic bronchitis, etc. Only when inflammation occurs in the respiratory tract, there is congestion, edema and increased mucus secretion in the mucous membrane, and these mucus and exudate irritate the airways, and the patient can show cough and sputum. If the sputum is mucous in nature, it may indicate the presence of acute bronchitis, asthma, pneumonia, etc. It may also be seen in chronic bronchitis and tuberculosis. If the sputum is purulent, it may indicate a purulent bacterial infection, and if there is blood in the sputum, it may indicate an infectious, vascular or malignant disease.