Chronic obstructive pulmonary disease (COPD) is closely related to venous thromboembolism (VTE). But it is difficult to identify VTE in COPD patients in clinical practice. Therefore, the prevalence data of PTE in COPD is limited. Pulmonary thromboembolism (PTE) is an important factor effecting patients outcomes, but existing researches only have short follow-up time less than 1 year. This study aim to develop an early detection system of PTE in COPD and explore the disease course and prognosis.