This study aimed to decipher the pharmacodynamic material basis and mechanism of herbal pair Bupleurum scorzonerifolium-Paeonia lactiflora(BS-PL) against liver cancer based on UPLC-Q-TOF-MS and network pharmacology. MTT assay and human hepatocellular carcinoma HepG2 cells were used to screen the effective part of BS-PL, the active components of which were further analyzed and identified by UPLC-Q-TOF-MS. Next, we applied Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP) to screen the active ingredients with OB≥30%. Then TCMSP and SwissTargetPrediction were used to collect and predict component targets, followed by the search of liver cancer-related targets with GeneCards and DisGeNET. The intersection targets were obtained using Venny 2.1.0. Protein-protein interaction(PPI) network was constructed using STRING to uncover the core targets, which were subjected to Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment analysis based on DAVID. Finally, the effects of active ingredients on the expression of main proteins enriched in the key pathways of HepG2 cells were verified by Western blot. The results indicated that compared with 30%, 50%, and 70% ethanol extracts of BS-PL, the n-butanol extraction part(CSYZ) from 95% ethanol extract of BS-PL exhibited the best anti-tumor effect. UPLC-Q-TOF-MS revealed 31 ingredients, 14 of which showed OB≥30%. A total of 220 intersection targets were obtained, from which 35 were selected as the key targets under the condition of two times the median of degree. Among the 215 items with P<0.05 obtained through GO enrichment analysis, 154 were classified into biological processes, 22 into cell components and 39 into molecular functions. KEGG enrichment analysis revealed 95 significantly affected signaling pathways, and the ones(sorted in a descending order by P value) closely related to the anti-liver cancer effect of herbal pair were PI3 K-AKT signaling pathway, TNF signaling pathway, MAPK signaling pathway, HIF-1 signaling pathway, and ErbB signaling pathway. Finally, the PI3 K/AKT signaling pathway involving the largest number of targets was extrapolated, and it was found that this pathway contained 15 core targets and 8 active components. Experimental verification showed that the effective components of BS-PL significantly inhibited the expression of p-PI3 K and p-AKT, consistent with the prediction results of network pharmacology. In conclusion, the main pharmacodynamic substances of BS-PL against liver cancer are 14 components like saikosaponin a, saikosaponin d, and paeoniflorin, which exert the anti-liver cancer effect by regulating PI3 K/AKT pathway.