All fifteen flavonoids (1-15) have been isolated from the roots of Sophora flavescens (Leguminosae) as active principles of the cytotoxic property toward human tumor cell lines such as A549, SK-OV-3, SK-Mel-2, XF498 and HCT15, in vitro. By means of spectral analyses, particularlyby the aid of various two dimensional NMR experiments, all $^1H-NMR$ ad $^{13}C$ -NMR signals of 1-15 were completely assigned, and thus the structures of 1-15 were established unambiguously.