Abstract: Background　As more autoimmune encephalitis (AC) related antibodies have been discovered, the clinical understanding of this condition has gradually improved. Anti-ATP1A3 antibody-related AC is extremely rare and has received very few reports both domestically and internationally. Its clinical characteristics and association with tumors remain unclear. Objective　 To summarize the clinical manifestations, laboratory tests, and prognosis of 4 patients with anti-ATP1A3 antibody-associated cerebellitis, and enhance the diagnostic awareness of such diseases. Methods　Clinical data about 4 patients diagnosed with anti- ATP1A3 antibody-related cerebellitis at Xi'an International Medical Center Hospital and Tangdu Hospital from January 2024 to April 2024 were collected. The clinical characteristics, laboratory tests, imaging examination features, and associated diseases of the patients were retrospectively analyzed. Results　The age distribution of the 4 patients was 28 to 68 years old, and there were 3 males and 1 female. All patients presented with unsteady gait or slow speech, and the cranial magnetic resonance imaging scan showed no abnormalities. The scale for the assessment and rating of ataxia (SARA) scale scores of all patients were above 6 points. The serum ATP1A3 antibodies of all patients were positive, and in 2 of them, the ATP1A3 antibodies in the cerebrospinal fluid were also positive. The white blood cell counts in the cerebrospinal fluid of 3 patients were all normal, while the cell count in the cerebrospinal fluid of 1 patient was slightly elevated. All 4 patients had no protein-cell separation in the cerebrospinal fluid. The head MRI of 4 patients was all normal. 1 patient was also diagnosed with small cell lung cancer. After receiving hormone therapy, the symptoms of 4 patients were relieved to varying degrees. After 3 months of treatment, the walking instability of 3 patients improved, while 1 patient was lost to follow-up. Conclusion　For patients with clinical manifestations of subacute or chronic ataxia, in addition to considering neurodegenerative diseases, the possibility of sporadic autoimmune-related cerebellitis should also be taken into account. The screening for subacute cerebellitis antibodies in cerebrospinal fluid and serum should be completed to better guide the diagnosis and treatment of the disease.