In this study, UPLC/Q-TOF-MS combined with multivariate statistical analysis(PCA,OPLS-DA) were used to investigate the effects of amic solution hydrolysis to extract of Radix astragalus . The analyses revealed that astragaloside Ⅳ is formed during sample preparation from acylated astragalosides like astragaloside I and astragaloside II when using amic solution to deal with the extract. Simultaneously, UPLC/Q-TOF-MS were used to determine the content of astragaloside Ⅰ, Ⅱ, Ⅳ of Radix astragali. This method could evaluate the quality of Radix Astragali effectively, and it is simple, sensitive and reliable.