Herpes simplex virus encephalitis is an acute infectious disease of the central nervous system caused by herpes simplex virus. With the development of laboratory and imaging techniques, early diagnosis of herpes simplex virus encephalitis is becoming increasingly possible, with imaging showing abnormal signals in the temporal lobe being suggestive and polymerase chain reaction detection of herpes simplex virus DNA in the cerebrospinal fluid being the current “gold standard” for diagnosis. Acyclovir treatment should be given as early as possible, and delayed treatment may lead to a poor prognosis.