Abstract: To analyze the chemical profile of Radix Bupleuri-Radix Paeoniae Alba in the serum, after oral absorption of the herbal pair, we used UPLC-QE-Orbitrap-MS technique and Compound Discover 2.0 software to compare the components in the extracts, and drug-containing serum. The map, based on the precise molecular weight and secondary fragment information given by the mass spectrometry, combined with the reference substance and reference information for, finding the chemical components in the blood after oral administration of the herbal pair in the rats. Animal experimentation was approved according to the Committee on the Ethics of Animal Experiments of Shanxi University. The results showed that a total of 55 components were detected in the serum, of which 16 were prototype components and 39 were metabolites of prototype components. UPLC-QE-Orbitrap-MS allows quick, accurate and comprehensive analysis of the blood components of the herb pair after oral administration. This preliminary study of the chemical components in the blood after herb pair ingestion provides a basis for the subsequent research on the pharmacodynamics and drug-drug interactions.