Anti-contactin associated protein-like 2 (CASPR2) antibody encephalitis is a rare autoimmune encephalitis with variable clinical symptoms and atypical imaging manifestations. The prognosis of the patients with severe disease is poor. Reversible posterior leukoencephalopathy syndrome is rarely reported in autoimmune encephalitis. The clinical data, diagnosis and treatment of a patient with anti-CASPR2 antibody encephalitis complicated with reversible posterior encephalopathy syndrome were reported, in order to improve the understanding of clinicians on the rare disease complicated with atypical imaging manifestations.