Abstract：Objective：To study the effect of Guipi tang on intestinal flora in patients with mild Alzheimer disease(AD) with deficiency of the heart and spleen type，and to explore the relationship between Guipi tang and intestinal flora in improving mild AD with deficiency of the heart and spleen type. Methods：Stool samples from 12 patients with mild AD with deficiency of the heart and spleen type were selected as study subjects，including samples before taking Guipi tang and samples after continuously taking Guipi tang for a month. The DNA of chromosome in each sample was observed and extracted，and the length of DNA fragments was detected and quantified. The 16S rRNA V3 region gene amplification and pyrosequencing were performed on the extracted DNA samples. Results：One month after the administration of Guipi tang，the overall structure of intestinal flora in AD patients was statistically different from that before administration， mainly manifested as decreased abundance of firmicutes，bacteroidetes，proteobacteria，actinomycetes and mycobacteria. In the two metabolic pathways of cell division and ether lipid metabolism， the average abundance of the patients before and after administration was statistically different(P＜0.05). The average abundance of microbe in cell division pathway after administration was higher than that before administration(P＜0.05)，and the average abundance in the ether lipid metabolism pathway after administration was lower than that before administration(P＜0.05). Conclusion：There is a strong correlation between the abnormal structure of intestinal flora and the occurrence and development of AD. Modified Guipi tang may be used to improve the symptoms of mild AD by changing the structure of intestinal flora.