Abstract: Twenty-five quinolizidine alkaloids (including matrine-type 1-14, sparteine-type 15-17, cytisine-type 18-23, other types 24 and 25) were isolated from the roots and rhizomes of Sophora tonkinensis by various chromatographic methods. Their structures were elucidated by physicochemical properties, NMR and MS spectral data. Among them, 12-(1-acetoxyethyl)-cytisine (23) is a new alkaloid derivative, and compounds 13, 16, 17, 24 were isolated from the roots and rhizomes of S. tonkinensis for the first time. Compounds 1, 6, 19 and 20 showed potent inhibitory activity against LPS-induced NO production in RAW 264.7 macrophages, with IC₅₀ values of 39.86 ±0.65, 23.66 ±0.37, 34.56 ±0.45, 47.68 ±0.58 μmol·L^-1, respectively.