Chronic Obstructive Pulmonary Disease (COPD) is one of the top three causes of death worldwide now. Acute exacerbations (AEs) of COPD are a risk factor for lung function deterioration, poor quality of life, longer hospitalization, and increased mortality. To date, COPD is associated with a heavy clinical and socioeconomic burden, of which AEs of COPD account for a significant part of the cost of patients with COPD. Although several retrospective cohort studies and post-hoc analyses from randomized controlled trials (RCTs) showed that AECOPD patients with higher blood eosinophils had a shorter length of hospital stay (LOS), lower doses of corticosteroid use, and better response to systematic corticosteroid treatment than those with lower blood eosinophils, the efficacy of systematic corticosteroids in AECOPD patients with higher blood eosinophils has not been confirmed by RCTs. Therefore, this study aims to evaluate if AECOPD patients admitted to hospitals with higher blood eosinophil levels could benefit from systemic corticosteroid therapy. In this study, all eligible AECOPD participants with peripheral blood eosinophil blood count >2% or > 300 cells/μL will be randomly assigned (1:1) to either a control group or a systemic corticosteroid group. The control group will receive an oral placebo of 40mg/day for five consecutive days in addition to standard treatment during emergency admission or hospitalization. And systemic corticosteroid group will receive oral prednisone 40mg/day for five consecutive days and standard treatment. This study will provide evidence on using peripheral blood eosinophil blood count to guide corticosteroid therapy in AECOPD patients and help the clinician make an individual decision for each patient.