In the present study, the chemical components of Qinghao Biejia decoction (QBD) were qualitatively and quantitatively analyzed using UPLC-Orbitrap Fusion-MS/MS and UPLC-QQQ-MS/MS techniques, followed by identification of each component's origin and evaluation of the antibacterial activity of QBD and its components.High-resolution mass spectrometry was used to obtain information on the precise molecular weight, retention time, and fragmentation ion peaks of the compounds used to identify the components of QBD and establish a method for their quantification. In vitro assays including determination of the minimal inhibitory concentration and growth curves were used to assess the antibacterial activity of QBD and its components.A total of 39 components, including fatty acids, phenolic acids, amino acids, flavonoids, coumarins, terpenoids, and alkaloids, were identified by UPLC-Orbitrap Fusion-MS/MS. A high-performance analytical method was also established to quantify 12 components of QBD. The content of mangiferin was relatively high (estimated to be 814 μg/g). The results of the antibacterial assays indicated that mangiferin exhibits antibacterial effects against two strains causing respiratory tract infections.The present study suggests that mangiferin may serve as a natural compound which shows high antibacterial activity. The results can aid the discovery and analysis of the active antimicrobial components present in QBD and further provide a reference for quality assessment of multi-component herbal prescriptions.© 2022 John Wiley & Sons Ltd.