To explore the clinical significance of peripheral blood neutrophil-to-lymphocyte ratio (NLR) in idiopathic inflammatory demyelinating diseases (IIDDs) of the central nervous system. Methods: The subjects comprising 81 IIDDs patients from Tongji Hospital in Wuhan included 23 neuromyelitis optica spectrum disorders (NMOSD) patients, 19 myelin oligodendrocyte glycoprotein antibody associated diseases (MOGAD) patients, 25 multiple sclerosis (MS) patients, 14 autoimmune glial fibrillary acidic protein astrocytopathy (A-GFAP-A) patients, and 20 non-inflammatory neurological disease patients as controls (CTLs). The Expanded Disability Status Scale (EDSS) was used to assess disease severity, and routine blood testing was performed to compare the peripheral blood NLR between the control group and each case group. The relationship between NLR and disease severity was explored. Results: The NLR in patients with NMOSD (P=0.01844) and A-GFAP-A (P=0.0014) were significantly higher compared to the control group, while there was no significant difference in the NLR in patients with MOGAD (P=0.095) and MS (P=0.205) compared with the control group. There was no correlation between EDSS scores and NLR (P>0.05) . Conclusion: NLR is elevated in patients with NMOSD and A-GFAP-A, while no association was found between NLR and disease severity.