After carbon monoxide poisoning, patients develop delayed encephalopathy about one month after acute poisoning. After carbon monoxide poisoning, carbon monoxide binds closely to hemoglobin, which in turn reduces the ability of hemoglobin to carry oxygen, leading to a state of hypoxia in the body, and brain cells are most sensitive to hypoxia. After carbon monoxide poisoning, not only should the patient be transferred to a well-ventilated place as soon as possible, but also be treated with hyperbaric oxygen in a regular hospital as soon as possible, and be given symptomatic and supportive treatment such as nutrition of brain cells. Hyperbaric oxygen is effective for acute carbon monoxide poisoning and delayed encephalopathy of carbon monoxide poisoning, and it is important to insist on using sufficient amount of hyperbaric oxygen therapy. After carbon monoxide poisoning, the patient’s condition should be closely monitored, and once there is impaired physical activity or change in consciousness, the patient should be alerted to the emergence of delayed encephalopathy and be treated at a regular hospital as soon as possible.