Objective: The features of clinical, laboratory and radiologic examinations of an adult patient with Japanese encephalitis (JE) were analyzed to understand the differences in clinical characteristics between adult and children patients, and to investigate the method of etiological tests. Methods: The clinical, laboratory tests and radiographic data of an adult case with JE requiring hospitalization were analyzed retrospectively and the related literature was reviewed. Results: The clinical presentation of patients with JE was nonspecific, the patient presented with fever, consciousness and cognitive impairment, convulsion and meningeal irritation. Its main test indicator is IgM antibody of Japanese encephalitis virus(JEV) in acute cerebrospinal fluid and serum specimens.Craniocerebral MRI is an important auxiliary examination for JE, the common sites involved are thalamus, basal ganglia and cerebral cortex, of which thalamus is almost 100% affected. Conclusions The clinical presentation of patients with JE was nonspecific. Clear diagnosis should be accompanied by the combination of epidemiology, laboratory tests and specific antibodies detection. Neural damages commonly occur in thalamus.