The peak of cerebral edema in craniotomy is usually 10-14 days after the surgery, which is a peak period, so it must be taken seriously, but before that, a corresponding process will gradually develop. Generally speaking, the first stage is due to the change of blood flow in the blood vessels, which causes the manifestation of brain tissue edema. For example, after craniotomy, some blood vessels are electrocoagulated, and some vessels are restored to patency, so the intracranial blood flow is in the process of readjustment. The second stage is the stage of cellular edema, because at this time the intracranial area often produces certain chemicals due to some blood accumulation, or some blood leakage. The human body will also produce certain factors in the process of absorption, which may stimulate the nerve cells and the surrounding glial tissues, thus producing some edema performance, and the combined effect of the two factors will then cause edema and swelling of the brain. Therefore this time must be in the early stage of the corresponding prevention in a timely manner.