Abstract： Objective:To analyze the clinical and imaging features of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients with different levels of blood eosinophil (EOS).Methods:This was a case-control study.The convenience sampling method was adopted, and the clinical and imaging data of 261 patients with AECOPD who were hospitalized in the Department of Respiratory and Critical Care Medicine of the Affiliated Central Hospital of Shenyang Medical College from December 2020 to December 2021 were collected and analyzed statistically.(1) According to the EOS level (EOS%), the patients were assigned into 2 groups including the EOS (EOS≥2%)group and non-EOS (EOS<2%) group.The general data, the course of disease, hospital stay, hormone use and non-invasive ventilation, white blood cell(WBC) count, neutrophil percentage(NP), lymphocyte percentage, neutrophil-lymphocyte ratio (NLR), arterial partial pressure of carbon dioxide, arterial partical pressure of oxygen, C-reactive protein (CRP), forced expiratory volume in the first second percent predicted, maximum mid expiratory flow, Global Initiative for Chronic Obstructive Lung Disease Grade, modified Medical British Research Council dyspnea scale, COPD Assessment Test, lung volume (LV) and emphysema index (EI) of left, right and whole, airway volume percent were included as a comparison.(2) The patients were divided into two strata based on conditions whether they smoked or not, and the imaging indicators of the patients in the EOS and non-EOS groups under smoking and non-smoking conditions were assessed respectively.Two independent samples t test, rank sum test, and chi-square test were used for statistical analysis. Results:Compared to the non-EOS group, the disease duration was shorter in the EOS group ( Z=3.42, P=0.001), WBC count, NP, NLR, CRP were lower ( Z=4.54, t=7.60, Z=5.02, Z=3.93, all P<0.05), the percentage of lymphocytes was higher ( Z=4.77, P<0.001).In the non-smoking patients, right LV(2 366.89[1 898.34, 2 935.38] ml vs 2 821.64[2 130.17, 3 385.92] ml), right upper LV (878.15[647.64, 1 051.62] ml vs 1 017.29[902.92, 1 443.13] ml), left LV (1 957.46[1 612.56, 2 442.3] ml vs 2 397.63[1 943.31, 2 974.42] ml), left upper LV ([1 019.00±324.52] ml vs [1 259.09±359.07] ml), total LV (4 275.65[3 399.91, 5 378.75] ml vs 5 269.44[4 067.70, 6 330.72] ml), left EI (0.06[0.03, 0.12] % vs 0.12[0.07, 0.20] %), whole EI (5.03[2.18, 13.09] % vs 9.99[5.59, 15.42] %) of the EOS group were significantly lower when compared with the non-EOS group ( Z=2.38, Z=2.73, Z=2.56, t=2.80, Z=2.48, Z=2.40, Z=1.99, all P<0.05). Conclusions:Smoking condition affects the imaging phenotype of AECOPD patients with different levels of blood EOS.The EOS%<2% shows severe emphysema in non-smoking conditions.