BACKGROUND Pharmacological studies indicate that Astragalus (AR) has various bioactivities, including anticancer, antiaging, anti-inflammatory, antiviral, and antioxidant activities. Flavonoids, saponins, amino acids, and polysaccharides are the main active components in AR. However, its complex chemical compositions bring certain difficulties to the analysis of this traditional Chinese medicine (TCM). Therefore, there is an urgent need to establish a method for rapid classification and identification of the chemical constituents in AR. OBJECTIVE To establish a method for rapid classification and identification of the main components of flavonoids, saponins, and amino acids in AR. METHODS The samples were analysed with ultra-high-performance liquid chromatography time-of-flight quadrupole mass spectrometry (UPLC-Q-TOF-MS) and data post-processing techniques. Firstly, fragmentation information was obtained in the positive and negative ion modes. Then, to realize the rapid classification and identification of AR components, the characteristic fragmentations (CFs) and neutral losses (NLs) were compared with information described in the literature. RESULTS A total of 45 chemical constituents were successfully screened out, including 22 flavonoids, 13 saponins, and 10 amino acids. CONCLUSIONS The established method realised the efficient classification and identification of flavonoids, saponins, and amino acid compounds in AR, which provided a basis for further study on AR.