Objective To explore the clinical significance of combined detection of serum endothelial cell-specific molecule 1 (ESM-1) and procalcitonin (PCT) in the acute exacerbation of chronic obstructive pulmonary disease (AECOPD) caused by bacterial infection. Methods A total of 200 AECOPD patients who were hospitalized in Department of Respiratory Medicine, Tinglin Hospital, Jinshan District, Shanghai from Jan. 2019 to Dec. 2021 were selected. They were divided into 2 groups based on the sputum culture reports: bacterial-infected group (n＝113) and non-bacterial-infected group (n＝87). As a control group, 100 volunteers who underwent health examination in Tinglin Hospital, Jinshan District, Shanghai during the same period were selected. The levels of serum ESM-1 and PCT in each group were detected by enzyme-linked immunosorbent assay. The diagnostic value of serum ESM-1 and PCT alone or in combination for AECOPD with bacterial infection was evaluated by receiver operating characteristic curves. Results Before the anti-infection treatment, the levels of serum ESM-1 and PCT in the AECOPD bacterial-infected group were significantly higher than those in the AECOPD non-bacterial-infected group and healthy control group (all P＜0.05). After the antibiotic treatment, the expression levels of serum ESM-1 and PCT in the AECOPD bacterial-infected group were significantly decreased (both P＜0.05). The area under curve (AUC) values of serum ESM-1 and PCT alone in the diagnosis of AECOPD with bacterial infection were 0.902 and 0.828, respectively. The optimal critical value of ESM-1 was 1.326 μg/L, and the sensitivity and specificity in the diagnosis of AECOPD with bacterial infection were 0.836 and 0.842, respectively. The optimal critical value of PCT was 0.246 μg/L, and the sensitivity and specificity were 0.542 and 0.982, respectively. The best performance was achieved in the combination diagnosis with an AUC of 0.953, a sensitivity of 0.886, and a specificity of 0.952. Conclusion The levels of serum ESM-1 and PCT are increased in AECOPD patients with bacterial infection. The detection of serum ESM-1 combined with PCT has potential clinical value in improving the diagnosis rate of bacterial infection.