Cerebral edema is generally common in diseases such as head trauma, cerebral hemorrhage, massive cerebral infarction, and intracranial tumors. There is no exact data on the waking time of severe cerebral edema coma. If a severe coma with cerebral edema is not awake for a long time, it means that the extent of cerebral edema is relatively large or the cerebral edema is in more important parts, such as the brainstem and cerebellum, which seriously affects some nerve conduction factors that keep the body awake. The presence of cerebral edema usually reaches its most dangerous peak in about a week, after which it begins to gradually subside. The patient’s primary disease needs to be promptly identified and treated in conjunction with the results of various tests. If the cerebral edema coma is severe and the patient’s vital signs are not stable, the recovery time may take from one month to several months, or it may lead to a long-term coma or even a vegetative state. Treatment should follow the doctor’s protocol, such as dehydration, nourishing brain nerves, and improving circulation. While waiting, the comatose patient can be given nutritional support and provided with a quiet and comfortable sleeping environment. The family should remain calm, take more time to accompany the patient, wait patiently and pay close attention to the patient’s vital signs.