The clinical manifestations of paroxysmal sympathetic hyperactivity (PSH) after severe craniocerebral injury are very similar to those of grand mal seizures, which are easily misdiagnosed in the early stage, resulting in further irreversible brain damage. By comparing the similarities in clinical manifestations, seizure mechanism, drug treatment, and other differences of the above two, PSH can be identified clinically early. In this article, the common clinical manifestations and differences between PSH and grand mal seizures are listed by referring to relevant literature and combined with the nursing observation of PSH patients in the Department of Neurosurgery, the First Affiliated Hospital, Zhejiang University, School of Medicine in the past two years. Our research shows that PSH is a clinical syndrome that appears after a variety of acute brain injuries and is mainly characterized by hyperexcitatory sympathetic nerves. The clinical manifestations of PSH are complex and difficult to identify. Raising awareness of the syndrome is helpful for its early diagnosis and treatment.