Brain hemorrhage of 30mL is a moderate hemorrhage. Whether it is serious or not depends on the site of the hemorrhage, if it is located in the brain stem or cerebellum, the hemorrhage is relatively very serious. If it is located in the cerebral cortex, it is relatively not very serious, and the symptoms may be mild, but of course, some patients may be more serious. The brainstem is very narrow, and bleeding of 4-5mL is serious, and 30ml can easily lead to death; the cerebellum is located near the greater occipital foramen, in front of the brainstem, and bleeding of 30mL is enough to cause swelling of the cerebellum and compression of the fourth ventricle, leading to brain herniation. So these two areas, if the brain bleeds 30mL, may be life-threatening. If the 30mL hemorrhage is located in the cerebral hemispheres, lobes, such as the frontal and temporal lobes, and when the patient is an elderly person, it may cause less obvious symptoms. Because brain atrophy usually occurs in the elderly, the brain gaps are large and there is enough space to accommodate the expanding brain tissue, and the symptoms will not be severe. However, if the patient is younger, without brain atrophy, and there is little space in the skull, even if the hemorrhage is located in the cerebral hemispheres or lobes, a 30mL brain hemorrhage may cause serious consequences. Blood enters the brain tissue to form a hematoma after the blood vessel ruptures, and the hematoma compresses the brain cells, leading to ischemic necrosis of the brain cells, and the necrotic brain cells and the brain cells next to the compressed brain cells, as well as the completely necrotic brain cells, will produce edema and hematoma. This leads to severe swelling of the brain tissue, which may lead to the death of the patient. In the presence of cerebral hemorrhage, surgical treatment, such as craniotomy, is usually considered to remove the hematoma, while dehydration and reduction of intracranial pressure are given to improve the prognosis.