This study investigated the chemical constituents of Styrax tonkinensis (Pierre) Craib ex Hart. branches and leaves and their anti-atherosclerotic mechanism. The ethyl acetate extract of S. tonkinensis was isolated and purified using MCI, silica gel, ODS, Sephadex LH-20 column chromatography, and semi-preparative HPLC. Compound structures were identified through physicochemical properties, NMR spectroscopy, and literature comparison. Network pharmacology and molecular docking were employed to explore anti-atherosclerotic mechanisms. Nine compounds were isolated: 5α,6α-epoxy-3β-hydroxymegastigm-7-en-9-one (1), 3-hydroxy-β-ionone (2), E epipinoresinol (3), 9-methoxypinoresinol (4), puviatilol (5), (-)-eudesmin (6), methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate (7), 4-[[(3R, 4R)-4-[(3, 4-dimethoxybenzyl)methyl] tetrahydro-3-furanyl]methyl]-2-methoxy phenol (8), kaempferol (9). Among them, compounds 1, 2, and 4-9 were isolated from the genus Styrax for the first time. Network pharmacology results revealed that the nine compounds primarily target multiple proteins including prostaglandin-endoperoxide synthase 2 (PTGS2), albumin (ALB), and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA). KEGG pathway enrichment analysis identified key signaling pathways such as the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathways. This work provides the first systematic chemical analysis of S. tonkinensis branches and leaves, offering a foundation for further research.