Abstract: [Objective] To explore the mechanism of phytoestrogen biochanin-A(BA) inducing apoptosis of human osteosarcoma MG-63 cells and mitogen-activated protein kinase (MAPK)/apoptotic signaling pathway. [Methods] MG-63 cells that were treated with different concentrations of BA. MTT assay was used to detect the inhibition of cell viability. Cell apoptosis was detected by DAPI staining and Annexin V/PI flow cytometry. Western blot was used to detect the phosphorylation of MAPK signaling pathway related proteins and the expression of Bcl-2 and caspase family related proteins in mg-63 cells. [Results] BA effectively inhibited the cell viability of mg-63 cells in a time- and dose-dependent manner, and could induce MG-63 cells apoptosis. Approximately 40 μmol/L and 80 μmol/L BA was added on MG-63 cells for 48 hours, and the cell apoptosis rates were (45.28±3.79)% and (82.51±5.23)% respectively. Both were superior to that of the control group(5.31±3.14)％(P<0.05). The results of western blot showed that BA could promote the cleavage of caspase-9, caspase-3 and PARP (P<0.05), promote the expression of p-p38, p-JNK and Bax(P<0.05), and inhibit the expression of Bcl-2 (P<0.05) in a dose-dependent manner. [Conclusion] Biochanin-A can effectively inhibit the cell viability of human osteosarcoma MG-63 cells and promote cell apoptosis, and the mechanism of action may be achieved by activating MAPK/ apoptotic signaling pathway.