Pachymic acid (PA) is derived from Poria cocos. PA has a variety of pharmacological and inhibitory effects on various tumors. However, the mechanism of action of PA in gastric cancer (GC) remains unclear. To investigate the mechanism of PA in treating GC via the combination of network pharmacology and experimental verification. The GeneCards and OMIM databases were used to derive the GC targets, while the Pharm Mapper database provided the PA targets. Utilizing the STRING database, a protein-protein interaction network was constructed and core targets were screened. The analyses of Gene Ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis were conducted, and molecular docking and clinical correlation analyses were performed on the core targets. Ultimately, the network pharmacology findings were validated through in vitro cell assays, encompassing assessments of cell viability, apoptosis, cell cycle, cloning, and western blot analysis. According to network pharmacology analysis, the core targets were screened, and the PI3K/AKT signaling pathway is likely to be the mechanism by which PA effectively treats GC, according to KEGG enrichment analysis. The experimental findings showed that PA could control PI3K/AKT signaling to prevent GC cell proliferation, induce apoptosis, and pause the cell cycle. Network pharmacology demonstrated that PA could treat GC by controlling a variety of signaling pathways and acting on a variety of targets. This has also been supported by in vitro cell studies, which serve as benchmarks for further research.