The insoluble dietary fiber(IDF)was extracted from rice bran by using degreased rice bran as raw material.Four methods were used to extract rice bran cellulose,including sodium hydroxide-sodium chlorite,ultra-sonic-assisted sodium hydroxide-sodium chlorite,sodium hydroxide-hydrogen peroxide,ultrasonic-assisted so-dium hydroxide-hydrogen peroxide.The effects of four extraction methods on the structural and functional character-istics of rice bran cellulose were compared.The results indicated that ultrasonic assisted extraction of cellulose with sodium hydroxide and sodium chlorite had the highest purity(88.69%)and crystallinity(59.30%),and had better thermal stability,water retention,oil retention and glucose adsorption capacity.Compared with the sodium hydroxide-sodium chlorite method,the average particle size of cellulose extracted by the sodium hydroxide-hydro-gen peroxide method was smaller,the water holding capacity and oil holding capacity were weaker,and the cholate adsorption capacity and amylase inhibiting activity were stronger.FT-IR spectra revealed that the cellulose extracted by sodium hydroxide and hydrogen peroxide method contained a certain amount of lignin and hemicellulose.SEM analysis indicated that the surface of rice bran cellulose extracted by sodium hydroxide-sodium chlorite was smoot-her.Ultrasonic assisted treatment significantly improved the purity,water and oil retention of cellulose,but did not have significant effects on the average particle size and thermal stability of cellulose.