Medulloblastoma is a common tumor of the cerebellum, usually seen in children. Because the tumor is located in the posterior cranial fossa, it can easily block the cerebrospinal fluid circulation pathway and cause hydrocephalus, resulting in symptoms such as headache and vomiting. At the same time, because the tumor is located in the cerebellar earthworm, it can also cause unstable walking and other symptoms. These two factors are intertwined, resulting in children with medulloblastoma often having more severe symptoms, many of which require emergency treatment to save their lives. Although hydrocephalus caused by medulloblastoma blocking the four ventricles is secondary to the tumor, the increased intracranial pressure due to hydrocephalus can be fatal, so the hydrocephalus needs to be addressed at the same time as the medulloblastoma is surgically removed. In most cases, with the removal of medulloblastoma, the cerebrospinal fluid circulation pathway is opened and the hydrocephalus can be relieved without special treatment. However, sometimes hydrocephalus progresses rapidly, especially when the medulloblastoma grows rapidly and is large enough to cause severe hydrocephalus. In some children, the hydrocephalus must be temporarily resolved by means of extraventricular drainage before the tumor can be removed, in order to temporarily relieve the symptoms of hydrocephalus and protect the patient’s safety, and to obtain the opportunity to further remove the medulloblastoma. In other cases, if the cerebrospinal fluid circulation is not completely opened during the medulloblastoma resection, or if the child’s hydrocephalus is not relieved despite the opening of the cerebrospinal fluid circulation, the hydrocephalus needs to be further resolved by ventriculoperitoneal shunts before the follow-up treatment of medulloblastoma can be continued. Hydrocephalus caused by medulloblastoma with ventricular enlargement is a problem that must be properly addressed during the surgical treatment of medulloblastoma. The treatment plan for hydrocephalus combined with medulloblastoma needs to be selected according to the specific condition, and the cerebrospinal fluid circulation needs to be opened during the removal of medulloblastoma to reduce the possibility of reoperation for hydrocephalus after tumor removal.