Intracranial metastases are formed by the metastasis of some other malignant tumors. Don’t underestimate it, because intracranial metastases are also prone to multiple metastases, which will bring more troubles to patients’ lives, so this disease must be treated promptly when it is found in the early stage. Intracranial metastases can be divided into the following three categories according to the site of metastases: 1. Cranial and dural: the primary tumors are mostly prostate cancer, breast cancer, lymphoma, melanoma, neuroblastoma, osteosarcoma, etc. From the surgical point of view, these metastases are not as important as brain parenchymal metastases, but if the superior sagittal sinus or transverse sinus is compressed or the cranial nerves are involved, it will cause obvious symptoms. 2. Soft meninges and arachnoid: also known as meningeal metastasis or cancerous meningitis, although such metastasis can occur in all malignant tumors, it is less common than brain metastasis, with an autopsy detection rate of 8%. It is mostly seen in acute leukemia, non-Hodgkin’s lymphoma, breast cancer, lung cancer, and melanoma. Hematogenous origin is the main route of dissemination, but also meningeal dissemination can be caused by brain metastases (commonly breast cancer). Therefore, the anterior part of the basal and lateral fissure pools are the preferred sites. It presents with arachnoid thickening, grayish opacity, dissemination with tumor nodules and punctate hemorrhage, soft meningeal fibrous degeneration, cancer cells and inflammatory cell infiltration. There may be tumor deposits on the choroid plexus and ventricular wall. 3.Brain parenchyma: It is a common intracranial metastatic route, with an incidence of 16%-18%. Common primary tumors are from lung, choroidal epithelium, breast, gastrointestinal tract, kidney and melanoma. They can be solitary or multiple. Metastases can be distributed in any part of the brain. Since they are mainly disseminated through arteries, cancer emboli tend to be retained at the end of arteries (especially the middle cerebral artery), so supratentorial (5/6) brain metastases are more common than infratentorial (1/6) ones. Supratentorial metastases are more common in the frontal, parietal, and temporal lobes, accounting for more than 70% of cases, while subratentorial metastases are more common in the cerebellar hemispheres. Other rare sites are basal ganglia, hypothalamus, pituitary gland, brainstem, choroid plexus, pineal gland, fourth ventricle, semilunar ganglion, and optic or olfactory nerves.