To establish a method for determination of astragaloside IV in Radix astragali by UPLC-MS/MS.Methods Radix astragali was extracted with methanol-ammonia (3∶1, V/V) for 30 min by ultrasonic, the astragaloside IV was monitored via the ESI+ionization model and quantified by multiple reaction monitoring(MRM), using m/z 785.4/143.108 and m/z 785.4/473.391 as qualitative ion pair and m/z 785.4/143.108 as quantitative ion pair. Results The calibration curve of astragaloside IV was in good linearity over the ranges of 60.0-12 000 ng/ml (r=0.999 3), the average recovery was 91.7%, and the detection limit was 68.2 μg/kg. Conclusion This method was accurate, rapid, easy to operate, and the methodology validation showed that it was suitable for the determination of astragaloside IV in Radix astragali.