Objective To analyze the influence of Helicobacter Pylori （HP） infection on the plasma oxidative stress state and platelet mitochondrial function in patients suffered Parkinson disease （PD） and to determine the role of HP infection in the pathogenesis of PD. Methods Fifty-three patients with PD and fifty age-matched control subjects were analyzed. Plasma IgG against HP were measured by western-blot. Plasma MDA, GSH level and platelet mitochondria complex activity Ⅰ were measured by spectrophotometry. Results The seropositivity for HP antibody and type Ⅰ infection were significantly higher in PD group than in control group （P〈0.05）. Platelet mitochondria complex Ⅰ activity： there were significant differences between PD group and control group （P〈0.05）, PD（HP^＋） group and control（HP^- ） group （P〈0. 057. Plasma MDA content： there were no significant difference between PD group and control group （P〉0.05）, but significantly different between PD （HP^＋） group and control （HP^- ） group （P〈0.05）. Plasma GSH content： there were no significant difference between PD group and control group （P〉0.05） or among PD （HP^＋）, PD（HP^-）, control （HP^＋）. and control （HP^-） groups （P〉0.05）. The platelet mitochondria complex Ⅰ activity was negatively correlated with UPDRS scores （P〈0.05） and there was no correlation between complex Ⅰ activity and age or duration, plasma MDA and UPDRS scores, age or duration. The plasma GSH was negatively correlated with duration （P〈0.05）, and there were no correlation between plasma GSH and UPDRS scores or age. Conclusions HP infection caused systemic oxidative stress and mitochondria dysfunction in definite tissues, that might participated in the pathogenesis of PD.