To develop a method for measurement of astragaloside Ⅳ in the Radix astragali from Guizhou province.The Radix astragali was extracted with methanol and the extraction repeated for three times.The theoretical plate number of astragaloside Ⅳ was 5 588,the resolution 1.621 and the tailing factor 1.113.The calibration curve was linear in the range of 4.400~440.0 μg/mL,Y=1.404 8 X+16.682,R=0.999 0.The Intra-day and inter-day precision(RSD) were all less than 1.5%,the recurrence(RSD) was 0.67%(n=5).The limit of detection was 0.440 μg/mL,the recovery 98.9%,96.7%,99.8%,and RSD 2.8%、3.5%、2.5%(n=5) respectively for astragaloside Ⅳ.Our developed method can shorten the time used for Radix astragali pretreatment,and is a simple and reliable method to determine the content of astragaloside Ⅳ in Radix astragali.The results also prove that the quality of Radix astragali in Guizhou Province is relatively good.