Objective:To investigate the effects and mechanisms of anti-cancer by bacailein combined with U0126 on human breast cancer in vitro. Methods: The human breast cancer cell line MCF-7 was treated by baicalein,U0126 and baicalein combined with U0126 respectively. CCK8 assay measured cell proliferation of MCF-7;flow cytometry tested the cell cycle and apoptosis of MCF-7;microscopy observed the amount;TUNEL assay evaluated the apoptosis of MCF-7;Western blot detected the protein level of proliferation and apoptosis related protein;scratch assay measured the ability of migration. Results: Human breast cancer cell line MCF-7 was treated by baicalein or U0126 at different concentration for 24 h, CCK8 assay suggested that both of them can dramatically inhibit MCF-7 proliferation in a dose-dependent way (P<0. 05). Compared to the blank and DMSO groups,the human breast cancer cell line MCF-7 was treated with baicalein for 24 h,the cellular rate at G0-G1 phase increased a lot (91%) (P<0. 05),while the cellular rate at S phase reduced dramatically (P<0. 05),cell apoptosis increased dramatically by microscopy and TUNEL assay(P<0. 05),the level of ERK1/2,CyclinD1 and JNK reduced quickly (P<0. 05). Compared to the baicalein group,MCF-7 was treated by baicalein combined with U0126,the cellular rate at S phase decreased remarkably (P<0. 05),apoptosis was much obvious (P<0. 05),the phosphorylation level of ERK1/2 and JNK reduced a lot (P<0. 05),and the proliferation accelerator CyclinD1 highly decreased (P<0. 05);the scratch assay demonstrated that cell migration was dramatically inhibited when MCF-7 was treated by 20 μmol/L baicalein ( P<0. 05 ) . Conclusion:Both of baicalein and U0126 can inhibit the proliferation and migration,induce the apoptosis of human breast cancer cell line MCF-7 through decreasing the level of ERK, JNK and CyclinD1. Baicalein and U0126 can provide some novel avenues to treat breast cancer in clinic.