Abstract: OBJECTIVE  To qualitatively analyze the chemical compositions of classical prescription Shaoyao Gancao Decoction by UHPLC-Q-Exactive Orbitrap MS.METHODS  The analysis was performed on Thermo Scientific Hypersil GOLD C₁₈ column (100 mm×2.1 mm, 1.7 μm) with mobile phase of acetonitrile (A)-0.1% formic acid water solution (B) for gradient elution at a flow rate of 0.3 mL·min^-1 under 30 ℃. The UHPLC-Q-Exactive Orbitrap MS was equipped with a HESI-Ⅱ ion probe and MS¹and MS² data of samples were collected in positive and negative ion modes.RESULTS  A total of 129 constituents were identified from Shaoyao Gancao Decoction according to the precise molecular weight, fragment ion information, reference substance identification and related literature reports, including 82 flavonoids, 20 terpenoids, 10 phenolic acids, 7 coumarins and 10 other compounds.CONCLUSION  UHPLC-Q-Exactive Orbitrap MS technology is used to comprehensively analyze and identify the chemical constituents in Shaoyao Gancao Decoction, and the mass spectrographic cracking characteristics of the main chemical constituents are preliminatively summarized, which provides a reference for the quality control and pharmacodynamic material basis.