Objective: To research the effects of flavonoids of Astragalus complanatus(FAC) on proliferation,apoptosis and expressions of p53,c-My and NF-кB in human breast cancer MCF-7 cells. Methods:The inhibit rate of MCF-7 cells treated by different concentration of FAC was studied by MTT at different times. The apoptosis rate of MCF-7 cell was essayed by flow cytometry after treated with effective concentration of FAC and time points according to MTT. The expressions of p53, c-Myc and NF-кB were quantified by fluorescence immunoassay and Western blot. Results:According to MTT,0.0625,0.125,0,25,0.5 mg/ml of FAC treated for 24 h, 48 h,72 h markedly inhibited proliferation of MCF-7(P < 0.05,vs control). According to flow cytometry, MCF-7 was induced to apoptosis by FAC. After 72 h treatment with FAC(0.0625,0.125,0.25,0.5 mg/ml), the apoptosis rates were 6.5%,18.3%,49.6% and 57.9%,respectively. The expression of p53 was up-regulated, while c-Myc and NF-κB were markedly reduced detected by fluorescence immunoassay and Western blot. Conclusion:FAC could inhibit proliferation and induce apoptosis of MCF-7. Its role may be related to decreased expression of NF-кB and c-Myc, increased expression of p53.