Pulmonary hypertension is a common complication of chronic obstructive pulmonary disease (COPD). It is reported that over half of COPD patients develop pulmonary hypertension. COPD and pulmonary hypertension may have pathological or genetics interactions so that patients having both disorders tend to have poor prognosis. Echocardiography is widely used to detect pulmonary hypertension, but it's not accurate enough. Therefore, high-quality data reflecting the prevalence, disease course and outcome of pulmonary hypertension in COPD is very limited in China. The aim of the study is to detect pulmonary hypertension with right heart catheterization, describe its outcome in Chinese COPD patients and explore the underlying interaction mechanism.