The sputum of bronchiectasis is more clearly characterized, it is divided into three layers, the first, foam-like substance, in which purulent components can be suspended. The second layer, a turbid mucus-like substance, is more brightly colored. The third layer, a necrotic deposit due to the endothelium of the bronchial tubes or infection. The diagnosis of bronchiectasis is based on a comprehensive history, symptoms, signs, and relevant imaging data, examination, especially chest CT, chest CT if there is a clear sign of seal or double track sign, and then combined with the aforementioned diagnostic basis to diagnose bronchiectasis.