Objective:To investigate the relationship between anti-Helicobacter pylori antibody(Hp-IgG)and anti-aquaporin 4 antibody which are in neuromyelitis optica(NMO)and multiple sclerosis(MS).Methods: Serum specimens were collected from the 33 patients with MS,7 patients with NMO,and 35 health examination cases.Hp-IgG were detected by enzyme-linked immunosorbent assasy and anti-aquaporin 4 antibody were detected by cell based assay respectively.The positive rate of Hp-IgG and anti-aquaporin 4 antibody were analyzed,and the difference of Hp-IgG positive rate was compared between patients with Hp-IgG positive and negative.Results: Serum Hp-IgG positive rate of MS,NMO and normal control groups were 69.70％,85.71％ and 42.86％ respectively with a significant statistically difference of Hp-IgG(P<0.05).Positive rate of serum anti HP-IgG antibody in MS group,NMO group and normal control were significantly different(P<0.05);but there was no statistical significant difference of anti HP-IgG antibody positive rate between MS group and NMO group(P>0.05).Serum anti AQP4 antibody positive rate of MS,NMO and normal control groups were 4.2％,85.71％ and 0％ respectively with a significant statistically difference of anti AQP4 antibody(P<0.05).The positive rates of anti HP-IgG which were in MS patients and NMO patients with positive anti AQP4 antibody were 72.73％,the positive rates of anti HP-IgG which were in MS patients and NMO patients with negative anti AQP4 antibody were 79.31％,the difference was not statistically significant(P>0.05).Conclusion: HP infection is a risk factor for the occurrence of MS and NMO,but not associated with MS and NMO patients with anti AQP4 antibodies.