The supercritical CO₂ extraction of tocotrienols from hulless-barley was researched. The effects of temperature, pressure, ethanol concentration and extraction time on the extracting rate of tocotrienols were discussed with quadratic perpendicularity and universal rotation regression mathematical model. Extraction temperature has a significant effect (α=0.05) on the extracting rate of tocotrienols, while the ethanol concentration and extraction time have a very significant effect (α=0.01) on the extracting rate of tocotrienols. The interaction between pressure and ethanol concentration has a significant effect on the extraction rate of tocotrienols, but not the extraction pressure alone. The optimum SFE-CO₂ parameters for extracting tocotrienols are the extraction temperature 51.8℃, the pressure 34.7 MPa, the ethanol concentration 9% and the extraction time 120 min.