Hypercapnia is defined as a partial pressure of carbon dioxide higher than 50 mmHg in blood gas analysis. It is mainly seen in type II respiratory failure, and its etiology mainly includes acute exacerbation of chronic obstructive pulmonary disease, emphysema, and chronic bronchitis. When hypercapnia occurs, the following points should be taken for treatment. 1. Give the patient continuous low-flow oxygen, the oxygen flow should be less than 2L/min. 2. If the effect of continuous low-flow oxygen is not good, consider non-invasive ventilator-assisted breathing to help eliminate excessive carbon dioxide from the body. 3. If necessary, perform tracheal intubation and give mechanical ventilation.