To investigate the anti-mutagenic action of the total flavonoids of Astragalus (TFA).Three groups of concentrations of TFA and one inducer group were used. The anti-mutagenic action of TFA was studied by experiments in vitro and in vivo including miconucleolus assay, semen teraogenesis test and gene mutagenesis of V79/HGPRT.TFA did not affect the weight of the mice during the experiment period. The high concentration of TFA could significantly reduce cyclohophamide-induced miconucleolus number and gene mutagenesis of V79/HGPRT compared with inducer group. However, TFA did not make statistic change in the semen teraogenesis induced by mitomycin C.TFA has antimutagenesis effect.