Abstract: Oseltamivir phosphate（OP） is a specific drug for the treatment of influenza A and B. In this study, the effect of oseltamivir phosphate on human gut microbiota in vitro was investigated by using metagenome sequencing, gas chromatography and high-performance liquid chromatography, to provide data for the clinical application of oseltamivir phosphate from the perspective of gut microbiota. The results indicated that oseltamivir phosphate significantly reduced the relative abundance of Bacteroidaceae, Arachnia propionica, Ascomycota and Microviridae, and significantly increased the relative abundance of Streptococcus pluranimalium, Cronobacter turicensis and Basidiomycota（P＜0.05）. Additionally, oseltamivir phosphate slightly affected the relative abundance of Selenomonadaceae, Lactobacillaceae, Prevotellaceae, Megamonas funiformis, Limosilactobacillus mucosae, Prevotella copri, Bifidobacterium adolescentis, and the metabolic pathways and short-chain fatty acids（SCFAs） production. At the functional gene level, oseltamivir phosphate significantly affected the gene abundance of isocitrate dehydrogenase, D-aminoacyl-tRNA deacylase, and 7-carboxy-7-deazaguanine synthase（P＜0.05）. The degradation of oseltamivir phosphate by gut microbiota was different among the samples, and the average degradation rate was between 8.6% and 88.4% among different groups. In summary, oseltamivir phosphate has little effect on the human gut bacterial community, their metabolic pathway and metabolites during in vitro fermentation.