Chronic obstructive pulmonary disease (COPD for short) is a disease characterized by incomplete reversible airflow limitation that persists. the main symptoms of COPD are chronic cough, sputum, shortness of breath, and/or associated dyspnea. Generally COPD has a history of risk factor exposure, such as smoking, environmental pollution, organic dyes, etc. Smoking is the most significant risk factor for COPD. When there is a history of risk factor exposure, chronic cough, sputum and shortness of breath are present, early pulmonary function tests should be done, and pulmonary function tests are currently the gold standard for COPD diagnosis. COPD seriously affects the quality of life of patients and brings a heavy economic burden to families and society. However, COPD is preventable and treatable. It must be diagnosed early and treated early, with special attention to the treatment of the stable phase. Chronic bronchitis is a clinical definition in which cough and sputum are the main symptoms, and the onset lasts for 3 months every year for 2 years or more, and cough and sputum wheezing caused by other diseases are excluded. Chronic bronchitis is the most common cause of COPD, but not all patients with chronic bronchitis necessarily develop COPD. in other words, most patients with COPD have chronic cough, sputum, or wheezing, but not all patients with chronic cough and sputum will develop COPD.