Objective: To analyze the correlation between the intensity of spontaneous nystagmus (SN) and vestibular function in patients with acute vestibular neuritis (VN), and to clarify the quantitative relationship between the degree of semicircular canal dysfunction and the characteristics of SN. Methods: A total of 251 inpatients diagnosed with acute VN were enrolled in this study. All participants underwent comprehensive assessments including electronystagmography, rotational chair stop test, video head impulse test (v-HIT), and Dizziness Handicap Inventory (DHI) evaluation. Based on the intensity of SN, patients were stratified into three groups: 0~5°, 5~15°, and >15°. Statistical analyses were conducted to: compare DHI scores and rotational chair stop test Canal Paresis (CP) values among the three SN-intensity groups, evaluate the prevalence of abnormal v-HIT gain values in semicircular canals and compare horizontal, anterior, and posterior semicircular canal v-HIT gain values across the three SN-intensity subgroups. Results: A total of 251 acute VN patients were stratified into three groups by SN intensity: 0~5° (n=51, 20.32%), 5~15° (n=132, 52.59%), and >15° (n=68, 27.09%). Both DHI scores and CP values increased with SN intensity, and the differences between the three groups were statistically significant (P0.05). No significant between-group differences were observed in affected-to-healthy side v-HIT gain ratios across all three semicircular canals (P >0.05). Conclusion: In acute VN, SN intensity serves as a composite indicator of overall vestibular system involvement (encompassing peripheral lesion extent and central compensation status), likely reflecting widespread vestibular nerve involvement or abnormal central regulatory mechanisms rather than mere semicircular canal anatomical damage.