Background: There is limited evidence of the relationship between peripheral blood eosinophilia and clinical remission of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) at different ages, especially in elderly patients, which was the objective of the present study. Methods: This retrospective study stratified patients by age (>65 or ≤65 years) and analyzed the relationship between blood eosinophilia (≥2% or <2%) and AECOPD clinical remission at observing time points of 7, 10, 14, 21, and 28 days. Results: Of 703 AECOPD cases analyzed, 616 were elderly (>65 years), 272 of whom had eosinophilic exacerbations. There were statistically significant differences in leukocyte count, high-sensitivity C-reactive protein levels (hs-CRP), and overall and daily hospital costs between eosinophilic and non-eosinophilic AECOPD patients (p<0.05, respectively). In the overall analysis, eosinophilic exacerbation was significantly associated with a higher remission rate at 7 (hazard ratio [HR]=1.457 [1.072, 1.982]), 10 (HR=1.316 [1.108, 1.562]), 14 (HR=1.334 [1.102, 1.615]), 21 (HR=1.326 [1.125, 1.562]), and 28 days (HR=1.254[1.078, 1.459]). The subgroup analysis showed that eosinophilic exacerbation yielded better clinical remission than non-eosinophilic exacerbation in elderly patients (>65 years old) at 7 (HR=1.521 [1.084, 2.136]), 10 (HR=1.319 [1.096, 1.588]), 14 (HR=1.374 [1.118, 1.689]), 21 (HR=1.326 [1.112, 1.582]), and 28 days (HR=1.234 [1.049, 1.451]), while no differences were observed in middle-aged patients (between 45 and 65 years) at all time points (all p>0.05). Conclusion: The eosinophilic phenotype was associated with better clinical remission at 7, 10, 14, 21, and 28 days among elderly but not in middle-aged patients with AECOPD.