Inclusion Criteria:  1. Aged between 40 and 80 years old; 2. Current or former cigarette smokers (≥10 packs per year); 3. Spirometry-verified COPD (defined as postbronchodilator forced expiratory volume in the first second (FEV1)/ forced vital capacity (FVC) ≤ 0.70); 4. Within 72 hours of emergency admission or within 24 hours of hospitalization; 5. The initial absolute peripheral eosinophil count >150ul/L which was tested within 72 hours of emergency admission or 24 hours within hospitalization; 6. Current AECOPD meet the definition of AECOPD according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guideline; 7. Written informed consent before inclusion.  Exclusion Criteria:  1. Admission due to other diseases (pneumonia, pneumothorax, ect); 2. Participating in or completed another drug trial within 90 days; 3. Pregnancy or lactation; 4. Require invasive mechanical ventilation (IMV) or transfer to intensive care unit (ICU) within 24 hours after emergency admission or hospitalization; 5. With complications that may cause eosinophilia; 6. With pulmonary embolism in the past two years before emergency admission or hospitalization; 7. With myocardial infarction in the past four weeks before emergency admission or hospitalization, uncontrollable congestive heart failure or arrhythmia; 8. With comorbidity that may influence the immune system; 9. With neuromuscular disease affecting the respiratory system; 10. Pulmonary interstitial disease or active tuberculosis or bronchiectasis; 11. Systemic fungal infection; 12. Previous lung surgery, including thoracotomy or bronchoscopic lung volume reduction surgery; 13. Received prednisone ≥ 60mg in the past three days before emergency admission or hospitalization (or equivalent doses of other corticosteroid)； 14. Allergic or intolerant to corticosteroid; 15. Uncontrollable severe psychiatric illnesses even with medication, cognitive impairment, and severe language difficulties; 16. Life expectancy less than three months.