The appearance of granulation after bronchial stenosis surgery may be caused by scar hyperplasia, edema necrosis of the mucosa in the trachea, and repeated irritation. 1. Scar hyperplasia: If you have a scarred body, the scar formed by wound healing after bronchial stenosis surgery is likely to develop granulation. 2. Mucosal edema and necrosis in the trachea: If the trachea is intubated for too long, it will cause mucosal edema and necrosis in the trachea, and granulation will appear. 3. Repeated stimulation: If the sputum suction operation is not standardized during the operation, such as suctioning for too long, rough action, repeated stimulation of the trachea will cause damage to the mucosa of the trachea, causing infection and granulomatous hyperplasia. In addition, there may be tuberculosis divergent bacillus infection or immune dysfunction and other causes of granulation, the specific causes should go to the hospital to do a detailed examination, in order to treat the symptoms.