Sputum with bad odor may be related to diseases, such as lung abscess, bronchiectasis and other diseases. 1. Lung abscess: it is an infection caused by anaerobic bacteria in the lungs, the infected lung tissue, inflammation, necrosis, liquefaction, and ultimately the formation of pus cavities, the common symptom is coughing up pus-flavored sputum, in addition to fever and other symptoms. 2. Bronchiectasis: it refers to respiratory infections and bronchial obstruction, caused by bronchial suppurative inflammation, and ultimately lead to the destruction of the structure of the bronchial wall, the bronchial tube abnormal and persistent expansion of a class of diseases. The main clinical symptom is coughing up sputum, and the sputum is large amount of purulent sputum. There are many kinds of diseases that cause the odor of sputum, if you find the odor of sputum and other symptoms, affecting the daily life and rest, it is recommended to go to the regular hospital in time, complete the relevant examination, and follow the doctor’s instructions to treat the disease.