Coughing up foamy mucus sputum is one of the symptoms of chronic bronchitis, which is a chronic non-specific inflammation of the tracheobronchial mucosa and its surrounding tissues caused by infectious or non-infectious factors. Its pathology is characterized by hyperplasia of bronchial mucus glands and increased mucus secretion. Infection is one of the most important factors in the development of chronic bronchitis. Viral mycoplasma and bacterial infections are the main causes of acute attacks of the disease. Viral infections are common with influenza virus rhinovirus adenovirus and respiratory syncytial virus, bacterial infections are common with Streptococcus pneumoniae Haemophilus influenzae Catarrhella and Staphylococcus, bacterial infections occur every time secondary to viral or mycoplasma infections on the basis of damaged airway mucosa. . Diagnostic criteria for coughing up foamy mucus sputum: 1. Acute exacerbation refers to the appearance of purulent or mucopurulent sputum within 1 week, with a significant increase in sputum volume, or with inflammatory manifestations such as fever, or within 1 week “cough”, “sputum” or “wheezing Any one of the symptoms of “cough”, “sputum” or “asthma” is significantly aggravated, or the patient with severe disease is significantly aggravated. 2.Chronic prolonged period refers to those who have different degrees of “cough”, “sputum” and “wheezing” symptoms, which are prolonged for more than 1 month. 3.The clinical remission period refers to those who have been treated or naturally relieved, and whose symptoms basically disappear or occasionally have a slight cough and a small amount of sputum, and remain for more than 2 months.