Lung-brain syndrome, also known as pulmonary encephalopathy, refers to chronic chest and lung disease with respiratory failure, hypoxia, carbon dioxide retention caused by neuropsychiatric symptoms syndrome, is one of the serious complications of chronic pulmonary heart disease, most commonly seen in elderly patients with COPD. Clinical manifestations are mainly patients with progressive aggravation of dyspnea accompanied by neuropsychiatric disorders, such as confusion, excitement, mania, delirium, lethargy, somnolence, coma and so on. Arterial blood gas suggests that PCO2 increases, PO2 decreases, and pH decreases, and electroencephalography can be used as an important means of monitoring changes in the condition of patients with pulmonary encephalopathy. When the body is hypoxia, CO2 retention, acidosis can cause intracranial neuron swelling, edema, cerebral vasodilatation, capillary endothelial damage, increased permeability, and even coagulation dysfunction, hemorrhage, necrosis, etc., which can cause cerebral edema, increased intracranial pressure, and other causes of neuropsychiatric symptoms. The key to the treatment of pulmonary encephalopathy is the treatment of respiratory failure. In addition to routine low-flow oxygen, anti-infection, cough expectorant and asthma, correction of cardiac failure, rehydration of fluids to maintain the water and electrolyte balance, the most important therapeutic measures are to improve ventilation, increase oxygenation, eliminate carbon dioxide retention, alleviate respiratory muscle fatigue, and to buy the necessary time for treatment. For COPD patients, low-flow oxygen delivery is needed to slowly reduce CO2 concentration, to avoid CO2 syndrome resulting in a significant drop in blood pressure. It is recommended that patients go to regular hospitals for treatment according to their own symptoms in time, so as not to delay the condition and cause serious consequences.