Objective To investigate the clinical value of plasma copeptin in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Methods Ninety patients with AECOPD admitted between October 2013 and November 2015 were recruited as an AECOPD group, and 40 healthy subjects underwent physical examination simultaneously were recruited as a control group. According to patient history and severity, the AECOPD patients were divided into 3 groups: grade Ⅰ group (25 cases), grade Ⅱ group (45 cases) and grade Ⅲ group (20 cases). Plasma copeptin level was measured by enzyme-linked immunosorbent assay (ELISA). The changes of copeptin, the total counts of white blood cells (WBC), and C-reactive protein (CRP) of the AECOPD patients were compared before and after treatment. Then the correlations between plasma levels of copeptin and severity of AECOPD were evaluated. Results The plasma level of copeptin in the AECOPD group was higher than that in the control group [(16.4±5.2) pmol/L vs. (5.7±2.8) pmol/L, P<0.05), and gradually increased with the severity of AECOPD. For the AECOPD patients both before and after treatment, the copeptin concentrations were positive correlated with the plasma CRP concentrations and the total counts of WBC in blood (both P<0.05). Conclusions The plasma levels of copeptin gradually increase with the severity of AECOPD. The changes of plasma copeptin may be as an indicator for the severity of AECOPD.