S haoyao– G ancao decoction ( SGD ), a traditional C hinese formulae containing P aeoniae R adix and G lycyrrhizae R adix, is commonly used to relieve abdominal pain. It has attracted increasingly much attention as one of the most popular and valuable herbal medicine in clinic. However, the systematic analysis of chemical constituents of SGD are difficult to determine and thus remain unclear. In this paper, a rapid, sensitive, and reliable ultra‐performance LC ‐ ESI /quadrupole‐ TOF high‐definition MS ( UPLC ‐ ESI ‐ Q ‐ TOF ‐ MS ) with automated M etabo L ynx analysis in negative ion mode were established to characterize the chemical constituents of SGD . The analysis was performed on a Waters UPLC TM HSS T 3 (2.1 × 100 mm, 1.8 μm) using gradient elution system. MS / MS fragmentation behavior was proposed for aiding the structural identification of the components. With the optimized conditions, a total of 58 peaks were tentatively characterized by comparing the retention time and mass spectrometry data and retrieving the reference literatures. Of note, 44 ingredients were identified from G lycyrrhizae R adix, and 14 were from P aeoniae R adix. It is concluded that a rapid and robust platform based on UPLC ‐ ESI ‐ Q ‐ TOF ‐ MS was successfully developed for globally identifying multiple‐constituent of traditional C hinese medicine prescriptions. This is the first report on systematic analysis of chemical constituents and in vivo metabolites of SGD .