Objective To investigate the relationship of anxiety and depression mood with cognitive function in elderly patients with Parkinson's disease. Methods A total of 511 elderly Parkinson's disease patients who visited the 907th Hospital of the Joint Logistics Support Force of the Chinese People's Liberation Army from October 2024 to November 2025 were selected as the study subjects. The patients were divided into a cognitive impairment group (n=98) and a non-cognitive impairment group (n=413) based on the presence of cognitive impairment. The patient related data were collected. Disease severity was assessed using the modified Hoehn-Yahr (H-Y) staging scale, anxiety levels were evaluated with the Beck Anxiety Inventory (BAI), depressive symptoms were measured using the Geriatric Depression Scale (GDS), and cognitive function was assessed with the Mini-Mental State Examination. Logistic regression analysis was performed to identify risk factors for cognitive impairment in elderly Parkinson's patients, and Pearson correlation analysis was conducted to examine the relationship between anxiety/depression and cognitive function. Results Educational level (OR=5.348, 95% CI: 2.278-10.482), marital status (OR=6.056, 95% CI: 2.932-12.508), H-Y stage (OR=2.189, 95% CI: 1.433-3.345), BAI score (OR=1.270, 95% CI: 1.188-1.358), and GDS score (OR=1.340, 95% CI: 1.236-1.453) were all risk factors for cognitive impairment in elderly Parkinson's patients (P<0.05). Pearson correlation analysis showed that both BAI score and GDS score were negatively correlated with cognitive function (r=-0.383 and -0.400, respectively, P<0.001). Conclusion Educational level, marital status, H-Y stage, BAI score, and GDS score are all influencing factors for cognitive impairment in elderly Parkinson's disease patients, with both BAI scores and GDS scores being negatively correlated with cognitive function.