To investigate the correlation between uric acid (UA) level and mild cognitive dysfunction in newly diagnosed patients with Parkinson’s disease (PD). Methods: Eighty patients diagnosed with PD who had not yet undergone any treatment were selected as the PD group. At the same time, 70 individuals receiving routine examinations were randomly selected as the control group. Fasted levels of serum UA and creatinine (SCr) were measured in all individuals. Patients in the PD group were subdivided according to Hoehn-Yahr stage (H-Y stage) and mild cognitive impairment (PD-MCI) diagnostic criteria. Results: There was a significant difference between the serum UA and Montreal Cognitive Assessment (MoCA) values of the two groups (P<0.05). The mild cognitive impairment (PD-MCI) subgroup and no cognitive impairment (PD-NCI) subgroup both showed lower serum UA levels compared to the control group, and the PD-MCI subgroup showed lower UA levels than the PD-NCI subgroup (all P<0.05). For either male or female individuals, UA levels in both PD-MCI and PD-NCI subgroups were lower than those in the control group, and UA levels in the PD-MCI subgroup were lower than those in the PD-NCI subgroup (all P<0.05). For PD-MCI patients, MoCA scores in the early and middle subgroups were lower than those in the control group, and MoCA scores in the early subgroup were higher than those in the middle subgroup (all P<0.05). UA levels in early and middle subgroups were lower than those in the control group (both P<0.05). There was a positive correlation between UA level and naming ability of MoCA in PD patients, and there was not a significant correlation with other cognitive fields. Conclusion: The decrease of UA level may be one of the mechanisms for the occurrence of PD and decline of cognitive function.