Objective To observe the migration and inhibition mechanism of MicroRNA218-Robo1 pathway for breast cancer.Methods A total of 40 BALB/c-nu/nu femalemice were randomly divided into four groups.Each group was transfected over-expression MicroRNA218 MDA-MB-231 breast cancercells, co-over-expression MicroRNA218 and Robo1 MDA-MB-231 breast cancercells, knock-down Robo1 MDA-MB-231 breast cancercells and the control MDA-MB-231 breast cancercells.The tumor volume was examined every two weeks.Results Tumor volume of MicroRNA218 group was obviously less than control group, tumor volume of Robo1 knock out group was obviously less than common MicroRNA218 high expression and Robo1 group, the difference was statistically significant;MicroRNA218 and Robol knockout group than the control group, the increase in breast cancercellsapoptosis, cell proliferation and angiogenesis is restrained.Conclusions MicroRNA218 inhibited the migration of breast cancer by down-regulating the expression of Robo1.