Taking the fresh roots of Rehmannia glutinosa as raw material,oligosaccharides were extracted by ultrasonic and hot water methods,and two fractions of oligosaccharides (GRCP and GRSP) were obtained.The physicochemical properties and antioxidant activities of GRCP and GRSP were identified.The results indicated that carbohydrate contents of GRCP and GRSP were 901.39±0.73 and 948.06±5.03 mg/g,respectively,and they were mainly composed of galactose (51.39% and 51.56%,respectively),glucose (43.24% and 43.80%,respectively),and a small amount of arabinose,mannose,xylose,fructose,galacturonic acid and glucuronic acid.The FT-IR spectra indicated that GRCP and GRSP had infrared characteristic absorption peaks of sugars.The results of HPLC and MS indicated that oligosaccharides were the main components,especially the stachyose.The results of scanning electron microscopy showed that the surfaces morphologies of GRCP and GRSP were different.The thermal analysis results showed that the structures of GRCP and GRSP were stable below 205.5 and 209.0 ℃,respectively,which indicated that they had good thermal stability.Antioxidant experiment results showed that GRCP and GRSP both have certain antioxidant abilities.This study provides a theoretical basis for future in-depth research and utilization of polysaccharides from the fresh roots of Rehmannia glutinosa.