【Abstract】 Objective To investigate the effect of donepezil and Memantine on psychiatric symptoms and cognitive function of Alzheimer's disease (AD) patients.Methods 70 mild to moderate AD patients treated in our hospital were divided into A group and B group. A group was treated with hydrochloride. B group was treated with donepezil. The mental symptoms, cognitive function related indicators of changes and adverse drug reaction were observed. Results The efficacy of A group and B group were increased with time. MMSE, ADAS-cog, ADL and Blessed-Roth dementia scale scores of A group were significantly improved 3 months after treatment (P< 0.05). MMSE, GDS, ADAS-cog, Blessed-Roth, ADL scores of B group were improved 3 months after treatment (P< 0.05). There were no significant differences of MMSE, GDS, ADAS-cog, Blessed-Roth and ADL scores between A group and B group at 3,6, 12, 18 months (P> 0.05). At twentyfourth months, there were significant differences in MMSE, ADAS-cog and Blessed-Roth scores between the two groups (P< 0.05), while there was no significant difference between ADL and GDS (P> 0.05). The adverse reactions were gastrointestinal tract reaction during the treatment, which occurred the duration of drug dose increase. Conclusion Donepezil and memantine can improve the degree of dementia, cognitive function and ability of daily life for patients with AD. The shortterm effects of donepezil and memantine are comparable. There are no significant side effects.