Objective: To explore the application effect of memantine hydrochloride in the adjuvant treatment of Parkinson 's dementia. Methods: 60 patients with Parkinson 's dementia were randomly divided into control group (donepezil hydrochloride group) and observation group (memantine hydrochloride group), 30 cases in each group. Results: The total effective rate of the observation group was significantly higher than that of the control group (P<0.05), and the MMSE scale score was higher than that of the control group (P<0.05). There was no significant difference in the incidence of adverse reactions between the two groups (P>0.05). Conclusion: The clinical effect of memantine hydrochloride in the adjuvant treatment of Parkinson's dementia is significant, which is helpful for patients to restore their daily living ability and cognitive function as soon as possible. It is safe and worthy of clinical application.