To observe the changes of serum osteoprotegerin (OPG) level in patients with chronic obstructive pulmonary disease (COPD) complicated with pulmonary hypertension (PH) and explore its clinical value.Methods 120 COPD patients hospitalized in our hospital from December 2020 to December 2021 were selected as the observation group. According to the results of echocardiography, the patients were divided into COPD group and COPD complicated with PH (COPD-PH) group. The COPD-PH group was divided into mild, moderate and severe PH groups, and 49 healthy subjects were selected as the control group in the same period. The levels of serum OPG in each group were detected and compared. Results The level of serum OPG in COPD-PH group was higher than that in COPD group, and both groups were higher than that in the control group (P＜0.05); The serum OPG level in severe PH group was higher than that in moderate PH group, and both groups were higher than that in mild PH group (P＜0.05); The results of correlation analysis showed that serum OPG level was positively correlated with PASP, PLR, NLR, CRP and NT-proBNP (rs=0.463, 0.278, 0.396, 0.285, 0.273, P＜0.05), and negatively correlated with oxygenation index (rs =-0.415, P＜0.001). Conclusion The level of serum OPG in patients with COPD complicated with pulmonary hypertension increases, which is related to the degree of pulmonary hypertension. Dynamic observation of this index may monitor the occurrence and development of pulmonary hypertension in patients with COPD.