Abstract: The aim of this article is to screen the seaweed active material and study the effect on intestinal flora in mice with type 2 diabetes for providing functional nutrition food with hypoglycemic effect. First，the 35 different extracts from 13 kinds of seaweeds prepared by step-by-step extraction method were screened by evaluating in vitro α-glucosidase activity and using HepG2 insulin resistance cell model. Then，the impacts of extracts with solid hypoglycemic effects on intestinal flora in type 2 diabetic mice were evaluated through 16s rRNA high-throughput sequencing. Among the 35 seaweed extracts，55%-ethanol extracts from Lessonia nigrescens and Ascophyllum nodosum showed the most significant inhibitory effects on α-glucosidase activity；moreover，the 55%-ethanol extracts from L. nigrescens significantly increased the glucose consumption of insulin-resistant HepG2 cells，also remarkably increased the abundance of Bacteroidetes in the intestine of mice and decreased the number of Firmicutes bacteria. The 55%-ethanol extract of Lessonia nigrescens showed the most significant hypoglycemic activity and the ability to maintain the balance of intestinal microflora，which may have potential medicinal value.

Key words: Lessonia nigrescens, alcohol extracts, Diabetes mellitus, intestinal flora, 16S rRNA high-throughput sequencing