Severe fever with thrombocytopenia syndrome Bunyavirus can invade the nervous system and cause severe fever with thrombocytopenia syndrome encephalitis. Its clinical manifestations are non-specific, and pathogen detection is difficult. Clinicians have insufficient awareness, leading to potential misdiagnosis and underdiagnosis. This article reports a 59-year-old male patient with clinical major manifestations including fever, thrombocytopenia, consciousness disorders, and multiple organ failure. Viral encephalitis was considered clinically, but there was no pathogenic evidence. Metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid detected a novel Bunyavirus. After treatment with ribavirin, the patient's condition improved.