Objective:Detect the gut microbiota change in mice caused by 10 ％ short-chain inulin addition in high fat diet condition.Methods:8-week-old male C57/B6J mice,5 mice were fed with high fat diets,5 mice were fed with high fat diets with 10 ％ short-chain inulin addition.Fed 8 weeks and then collected fresh feces.Detected the three main short chain fatty acids in fresh feces.Extracted gut bacteria genome DNA for 16S rRNA V4 region sequencing.Principal Coordinate Analysis (PCoA),Alpha diversity and LEfSe analysis were performed to detect gut microbiota changes induced by short chain inulin.Results:Gut bacterial DNA amount and SCFAs amount per gram feces increased.PCoA analysis demonstrated fecal microbiota from inulin and control group mice had distinctive different features and clustered well.Inulin group owned lower fecal microbiota diversity compared with control group.LEfSe analysis revealed that in family level,Ｓ24_7 increased,Deferribacteraceae,Lachnospiraceae and Ruminococcaceae decreased.PICRUSt predicted that 22 level 2 KEGG Orthology groups changed.Conclusions:Inulin addition altered the gut microbiota composition in mice in high fat diet condition and impact the gut microbiota gene function.