The clinical data of 5 patients with autoimmune encephalitis admitted to the psychiatric department of the 904th Hospital of the Joint Logistics Service Force from January 2016 to June 2020 were retrospectively analyzed. Among 5 patients, 4 had stress psychological events within one month before the onset, and 3 had precursor symptoms such as fever and vomiting. They were all characterized by rapid progress of atypical mental and behavioral abnormalities and cognitive impairment. In terms of neurological symptoms, 1 case had faciobrachial dystonic seizures (FBDS), 3 cases had seizures, 2 cases had involuntary movement, and 4 cases had autonomic dysfunction, including central hypopnea, arrhythmia, blood pressure instability and paroxysmal facial flushing. Most neurological symptoms occur within 1 month of the onset. MRI revealed abnormalities in cerebral cortex, thalamus, temporal lobe and insular lobe in 4 cases; EEG demonstrated bilateral short-range medium amplitude θ wave in 2 cases. Abnormal cerebrospinal fluid (CSF) pressure was detected in 4 cases and 2 cases had abnormal cell number CSF. Three patients had positive anti-N-methyl-D-aspartate receptor (NMDAR) antibody, one patient had positive anti-LGI1 antibody, and one patient had positive anti-γ-aminobutyric acid B receptor (GABA BR) antibody. One case was discharged automatically, the remaining 4 patients were treated with glucocorticoid or combined with gamma globulin and cyclophosphamide, antiepileptic drugs, antipsychotic drugs and other symptomatic treatment, and their symptoms were relieved. Patients were followed up for six months, there was slightly slow residual reaction in 2 cases and personality change in 1 case. Autoimmune encephalitis characterized by mental symptoms is likely to be misdiagnosed as mental disorders. Clinicians should identify symptoms different from mental disorders, taking into account of the possibility of autoimmune encephalitis, to make early diagnosis and treatment.