Objective: To study the expression of miR-186 in serum exosomes of patients with chronic obstructive pulmonary disease, and to explore its clinical significance with chronic obstructive pulmonary disease. Methods: The peripheral blood sera of 53 COPD patients and 53 normal persons in our hospital were collected. Extraction of exosomes and electron microscopy to identify the characteristics of exosomes. RT-PCR method was used to detect the miR-186 expression level in serum exosomes. And statistical analysis of the expression difference between the COPD group and the normal group, alysis of the correlation between miR-186 and FEV1％ predicted value, and ROC curve analysis of the diagnostic value of serum exosome miR-186 in COPD. Results: The relative expression of miR-186 in serum exosomes of COPD group was 3.24 ± 0.14, which was significantly higher than that of normal control group 1.03 ± 0.04 (t = 15.47, P <0.001). The expression level of miR-186 was negatively correlated with the predicted FEV1％ of COPD patients (r =-0.5024, p <0.0001). The area under the ROC curve between miR-186 and COPD patients was 0.8409 (95％ confidence interval: 0.6875 -0.9943). Conclusion: The high expression of miR-186 in serum exosomes may be a risk factor and may be used as a diagnostic indicator of COPD.