Patients with lung abscess are usually accompanied by coughing up a large amount of purulent sputum, and their sputum has the following characteristics: 1. The amount of sputum is large, and patients with acute lung abscess can cough up several hundred milliliters of purulent sputum daily. 2. Patients’ sputum is mostly purulent and smelly sputum, which mostly suggests the combination of anaerobic bacterial infection, and about 60% of sputum is clinically smelly, which is mostly seen when the infection is mixed. 3. Patients with severe lung abscess can also appear the phenomenon of blood in sputum, and about 1/3 of patients can cough up blood to different degrees, leading to the formation of purulent blood sputum. 4, when the amount of sputum is large, the phenomenon of sputum stratification can be seen when sputum is stored in a container, usually in three layers, the upper layer is the foam layer, the middle layer is the mucus layer, and the lower layer is the sediment and necrotic purulent material, etc., according to the characteristics of sputum can better judge the disease, and according to sputum culture The sputum culture can help to treat the disease with sensitive anti-infective drugs.