Patients with Chronic Obstructive Pulmonary Disease (COPD) usually require continuous low-flow oxygen. Long-term home oxygen therapy is recommended for patients with COPD who have either of the following two conditions, and the duration of oxygen needs to be greater than 15 hours per day. ① Oxygen partial pressure ≤ 55 mmHg or oxygen saturation ≤ 88% with or without hypercapnia. ② Oxygen partial pressure 55-60mmHg, or oxygen saturation <89%, with pulmonary hypertension, right heart failure or erythrocytosis. Secondly, COPD patients should pay attention to the oxygen concentration when oxygen therapy, mainly low-flow oxygen-based, oxygen flow control in 1 ~ 2L / min. if the high concentration of oxygen to correct the patient's hypoxia, can make the patient's respiratory movement decreased significantly, resulting in CO2 retention, induced pulmonary encephalopathy and other serious complications. COPD patients should go to the hospital in time, and choose the appropriate treatment plan under the guidance of the doctor, do not blind treatment, so as not to delay the condition.