Anticoagulation is the most important treatment for pulmonary thromboembolism (PTE). The thromboembolism risk is especially high in patients with chronic obstructive pulmonary disease (COPD) exacerbations. However, there's no agreement on the most appropriate duration of anticoagulation in COPD with PTE to balance the risk of recurrence of thrombosis and bleeding. This randomized, controlled trial aims to evaluate the risk and benefit of prolonged anticoagulation compared with the regular 3-month anticoagulation in COPD with PTE.