Green sputum to yellow sputum is not necessarily in the recovery phase. According to clinical observation, the symptom of coughing up green sputum is usually related to Pseudomonas aeruginosa infection. Pseudomonas aeruginosa can invade the respiratory tract and cause inflammatory lesions when the body’s immunity is lowered. Because Pseudomonas aeruginosa infection tends to produce green pus, when this pus is expelled from the body with sputum, green sputum symptoms can occur. The change from green to yellow sputum can be considered to be the result of Pseudomonas aeruginosa infection being under control, but due to a combination of other bacterial infections. Streptococcus pneumoniae, Staphylococcus aureus and other bacteria invade the respiratory tract and produce yellow purulent secretions, which can lead to yellow sputum. At present, simply based on the green sputum to yellow sputum can not be sure that the patient’s condition is in the recovery stage, we need to actively go to the hospital, according to the blood biochemistry, chest radiographs and pathogenetic culture results to determine the type of the disease, and then according to the doctor’s instructions for treatment.