Objective:To explore the chemical basis for co-application of Paeonia lactiflora and Glycyrrhizae uralensis. Method:The contents of peoniflorin and glycyrrhizin were detected by using the method of high-performance liquid chromatography (HPLC) and the test methods in terms of specificity

linear range

precision

stability

repeatability and sample recovery were performed to determine the optimum chromatographic conditions. Result:The content of peoniflorin in P. lactiflora decoction was 2.19 mg·g-1; the content of glycyrrhizin in G.uralensis was 17.13 mg·g-1; the contents of peoniflorin and glycyrrhizin were 5.45

17.69 mg·g-1 respectively when P. lactiflora and G. uralensis were mixed together after decocting the component herbs singly; the contentsof peoniflorin and glycyrrhizin were 5.45

17.69 mg·g-1 respectively when P. lactiflora and G. Uralensis were decocted together. Conclusion:The contents of peoniflorinand glycyrrhizinwere promoted significantly with the former more significant when the component herbs were decocted singly and the contents of peoniflorinand glycyrrhizin was elevated greatly with the latter more significant when the component herbs were decocted together; the increase in contents of peoniflorinand glycyrrhizin may compose one of important reasons behind the synegetic analgesic potency when P. lactiflora and G. uralensis are used together.