Abstract: To establish the evaluation of quality standard of Radix Astragali according to their contents of Astragaloside Ⅳ and two flavoniods in Radix Astragsli from Gansu province and the standard of Radix Astragali. High-performance-liquid-chromatograph(HPLC) on a Kromasil ODS column (5 μm,4.6 mm×250 mm) with water-methanol gradient elution, at column temperature of 25℃, flowrate of 1.0 mL/min and wavelength at 254 nm for determenation of two flavoniods; with acetiontrile-water isocratic elution, at column temperature of 25℃, flowrate of 1.0 mL/min and wavelength at 200 nm for determenation of Astragaloside Ⅳ. Linear ranges of Astragaloside Ⅳ, 7-hydroxy-4'-methoxyisoflavone and 7,3'-dihydroxy-4'-methoxy-isoflavone were 1.215～6.075 μg, 2.325×10^-3～4.650×10^-2 μg and 2.350×10^-3～4.700×10^-2 μg respectively. The average recovery were 101.47%, 96.53% and 98.34% respectively, and relative standard deviations were 2.21%, 1.63% and 2.00% respectively. This method was practical and provided a new idea to study the quality standard of traditional Chinese drug.