Objective To investigate the intervention effect of praxoxyl combined with memantine on cognitive function in elderly patients with Parkinson's disease.Methods A total of 168 elderly patients with Parkinson's disease admitted to Department of Neurology, the First Affiliated Hospital of Henan University of Science and Technology were enrolled between January 2023 and January 2025. According to random number table method, they were divided into observation group (56 cases, pramipexole combined with memantine), control 1 group (56 cases, pramipexole) and control 2 group (56 cases, memantine). The clinical curative effect in the three groups was observed. Before and after treatment, activities of daily living [Barthel index, functional activity questionnaire (FAQ)], mental state [mini-mental state examination (MMSE)] and cognitive function [Montreal cognitive assessment scale (MoCA), neurobehavioral cognitive status examination (NCSE)] were evaluated. The incidence of adverse drug reactions in the three groups was observed. Results After treatment, scores of Barthel index, MMSE, MoCA and NCSE were increased, while FAQ scores were decreased in the three groups (all P<0.05). There was no significant difference in scores of Barthel index, FAQ, MMSE, MoCA and NCSE between control 1 group and control 2 group (all P>0.05). The scores of Barthel index, MMSE, MoCA and NCSE in observation group were higher than those in control 1 group and control 2 group, and FAQ score was lower than that in the two groups (all P<0.05). There was no significant difference in clinical response rate between control 1 group and control 2 group (P>0.05), but which in observation group was higher than that in the two groups (both P<0.05). There was no difference in the incidence of adverse reactions among the three groups (all P>0.05). Conclusion Both pramipexole and memantine can effectively improve activities of daily living, mental state and cognitive function in elderly patients with Parkinson's disease. Compared with monotherapy, curative effect of combined therapy is more significant, which can effectively and further improve clinical curative effect, with certain safety.