Brain tumors, including primary brain tumors and metastatic brain tumors, are one of the most challenging diseases in the field of central nervous system. This review briefly introduces the characteristics and immune mechanisms of different types of T cells, and focuses on summarizing the related research on T cell immune homeostasis in the brain and primary brain tumors such as glioblastoma, meningioma, medulloblastoma, pituitary adenoma, vestibular schwannoma, primary central nervous system lymphoma, as well as lung cancer metastatic brain tumors and breast cancer metastatic brain tumors. The aim is to reveal the interaction mechanism between T cell immune homeostasis and brain tumor disease progression, promote the elucidation of brain tumor pathogenesis, update clinical treatment strategies, and develop related drugs.