Herpes simplex virus encephalitis is the most common type of infectious encephalitis with a poor progno-sis,and some patients may develop recurrent or secondary autoimmune encephalitis.This article reports a case of anti-Ri antibody encephalitis secondary to herpes simplex virus encephalitis,in order to improve the understanding of this disease among clinicians and avoid misdiagnosis and missed diagnosis.Antibodies associated with paraneoplastic syndrome should be screened for patients with a previous history of tumor,and early diagnosis and immunotherapy play an important role in improving the prognosis of patients.