Paroxysmal sympathetic hyperactivity (PSH) has a profound impact on the prognosis of patients suffering from brain injury, but the research on pathogenesis in relation to PSH is limited. In this paper, the etiologies of PSH, including traumatic brain injury, hypoxic brain injury, cerebrovascular-related brain injury, craniocerebral infection, anti-N-methyl-D-aspartate receptor encephalitis, and a number of rare etiological factors were reviewed. The epilepsy hypothesis, disconnection hypothesis and new-presented neuroendocrine hypothesis about the pathogenesis of PSH were introduced, so as to provide reference for further research on PSH.