Permissive hypercapnia, as a lung protective ventilation strategy, has multiple organ protective effects. Studies have shown that permissive hypercapnia has protective effects on brain function. This article reviews the effects of permissive hypercapnia on cerebral blood flow, intracranial pressure, cerebral blood flow self‑regulation, cerebrovascular reactivity and cerebral oxygen metabolism, so as to provide theoretical basis for the later research of permissive hypercapnia and its application during clinical anesthesia.