There is still no perfect and unified classification method for closed cranial brain injury. For a long time, according to the degree of injury and pathological changes, the clinical classification of closed craniocerebral injury into concussion, brain contusion, brainstem injury and intracranial hematoma. This classification is actually quite unsatisfactory, and its main drawback is that it does not reflect the dynamic course of the disease, and there is a certain one-sidedness. Currently, the more common classification method used in China is to classify closed intracranial injuries into mild, severe and moderate types: 1. Clinical manifestations are: ① transient coma not more than half an hour. ②After waking up, there may be mild headache, dizziness, nausea, vomiting and other symptoms. ③ Near-event amnesia. ④Neurological examination and lumbar puncture are normal. 2. Medium-sized: mild cerebral contusion with or without skull fracture and subarachnoid hemorrhage. No signs of cerebral compression. Clinical manifestations are: ① Coma within 12 hours. ②Mild positive neurological signs are present. ③There are slight changes in body temperature, pulse, respiration, and blood pressure. 3. Heavy: extensive skull fracture, extensive brain contusion, brainstem injury or intracranial hematoma. Clinical manifestations are: ① deep coma or coma for more than 12 hours, or the appearance of re-coma. ② There are obvious positive neurological signs. ③There are significant changes in body temperature, pulse, respiration, and blood pressure. Each of the above types of injury, especially the moderate and severe types, can be aggravated or reduced by edema and hematoma, etc. It is sometimes difficult to immediately determine the type clinically and can often undergo transformation.