To study the mechanism of yam polysaccharide on insulin resistance in type 2 diabetes mellitus (T2DM) mice, C57BL/6 mice was selected and randomly assigned to the following groups:normal group, model group, low dose yam polysaccharide group, medium dose yam polysaccharide group, high dose yam polysaccharide group and metformin group. T2DM mice model was induced by feeding high fat diet combined with streptozotocin (STZ). After 6 weeks of continuous administration, serum were collected and fasting blood glucose (FBG), fasting insulin (INS), insulin resistance index (HOMA-IR) and insulin tolerance test (ITT) were determined. The abundance of intestinal flora was detected by 16S rRNA gene high-throughput sequencing, and the content of feces short-chain fatty acids (SCFAs) were detected by GC-MS. It was found that the level of serum FBG, FINS and HOMA-IR in each group of yam polysaccharide decreased significantly (P<0.01 ). The total amount and diversity of intestinal bacterial species in the yam polysaccharide group increased compared with type 2 diabetes mice. Firmicutes/Bacteroidetes ratio and Proteobacteria decreased at phylum level, Lactobacillus and Akkermansia significantly increased at genus level, while Enterobacter and Desulfovibrio significantly decreased compared with the model group. Compared with the model group, the intestinal SCFAs content of yam polysaccharide group were increased, and the upward trend of propionic acid and butyric acid was significant. The results showed that yam polysaccharide could improve glucose and lipid metabolism disorder and insulin resistance in T2DM mice, which might be related to the increase of total intestinal bacterial species and diversity, the change of bacterial community proportion and the increase of SCFAs. The aim of this study was to provide theoretical basis for yam polysaccharides development and utilization.