Optic neuritis (ON) is a general term for inflammation of any part of the optic nerve resulting from demyelination or infection. The number of patients with MOG-lgG antibody-related optic neuritis is increasing recently. Our study uses the fractional amplitude of low-frequency fluctuation (fALFF) method to compare the activity of specific brain regions in MOG-lgG ON patients and healthy controls (HCs). We selected a total of 21 MOG-lgG ON patients and 21 HCs were included in the study. All subjects underwent resting-state functional magnetic resonance imaging (rs-fMRI). The independent-samples t-test was used to compare demographic data and average fALFF values between groups. The specificity and sensitivity of fALFF values for distinguishing between MOG-lgG ON patients and HCs were evaluated by receiver operating characteristic (ROC) curve analysis. Pearson’s correlation analysis was used to analyze the relationship between fALFF values and clinical characteristics in MOG-lgG ON patients. Our results showed that fALFF values of the right cerebellum and left middle cingulum were lower whereas those of bilateral inferior temporal lobes, right gyrus rectus, and the left superior and right middle frontal lobes of MOG-lgG ON patients were higher than those of HCs (P 0.05). The average fALFF value of the left superior frontal lobe in MOG-lgG ON patients was positively correlated with Hospital Anxiety and Depression Scale score (HADS) (r = 0.6004; P 0.05) and duration of MOG-lgG ON (r = 6487; P 0.05). Thus, patients with MOG-lgG ON have abnormal activity in the brain regions related to vision. Changes in fALFF value can reflect functional sequelae of MOG-lgG ON, including abnormal anxiety or depressive emotional changes.