内容: The study investigated the effects of ethanol precipitation on the polysaccharide components obtained from 3 different oak acorns. The variables factors were ethanol precipitation times (1× or 2×), tree species (Quercus variabilis, Quercus aliena, Quercus dentata) and raw materials (whole acorn fruit or kernels). Through detections of acorn polysaccharide concentrations from different species and components analyses, we found that the second ethanol precipitation had a better extraction effect, and acorn polysaccharides were proved to be mainly composed of glucose, galacturonic acid, arabinose and galactose. Compared with other groups, the highest content of polysaccharides was proved to be extracted from Q. variabilis kernels, thus, acorn kernels should be suggested as the proper material for the extraction of acorn polysaccharides. Interestingly, acorn polysaccharides functionally alleviated liver and kidney damages in type 2 diabetes mice, they also had noticeable hypoglycemic effects and regulated insulin secretion, particularly in combination with metformin and D-mannuronic acid.