There are no reliable diagnostic criteria for Hashimoto encephalopathy (HE), and the diagnostic criteria proposed by Peschen et al. in 1999 are still used. Hashimoto’s encephalopathy can be diagnosed with unexplained recurrent myoclonus, grand mal seizures, neuropsychiatric abnormalities and at least 3 of the following 5 points: 1. EEG abnormalities. 2. Elevated thyroid autoantibodies (TPO/TG). 3. Elevated cerebrospinal fluid proteins or oligoclonal bands. 4, Steroid hormone therapy is effective. 5, Unexplained abnormal head MRI. Since thyroid autoantibodies are not specific markers for HE, and anti-NAE antibodies have been found in the serum and cerebrospinal fluid of patients with HE by Japanese scholars, and the responsiveness of patients to glucocorticoids has not been confirmed by prospective, controlled studies, this diagnostic criterion is still controversial. In addition, it is worth noting that HE is an exclusive diagnosis, and in the absence of sufficient evidence to diagnose other causes of extensive brain damage, the diagnosis of HE may be considered tentatively and experimental treatments such as hormones may be given; otherwise, HE should be diagnosed with caution, even though patients have high levels of thyroid autoantibodies, which may be present as derivatives of autoimmune reactions in other autoimmune encephalopathies or autoimmune encephalitis. in patients with other autoimmune encephalopathies or autoimmune encephalitis. We have diagnosed two patients, one with VGKC complex antibody encephalitis and the other with anti-NMDA receptor encephalitis, both of which were autoimmune encephalitis, and in both cases elevated thyroid autoantibodies were detectable, suggesting that we should be cautious in diagnosing HE clinically.