Objective：To explore the roles and the potential underlying molecular mechanisms of Osterix(Osx) on the migration and invasion of breast cancer cell line MDA-MB-231. Methods: Real-time PCR and Western blot assay were performed to detect the expression levels of lysyl oxidase (LOX) in Osx stably transfected or knocked down cells as well as in their corresponding control cells (231-OE6, 231-OEC, 231-KD2, and 231-KDC). The migration and invasion of 231-OE6 cells transfected with LOX siRNA and 231-KD2 cells transfected with LOX expression plasmids were detected by Transwell assays. Results: Compared to their corresponding control cells, the expression of LOX was increased in 231-OE6 cells, and decreased in 231-KD2 cells(P<0.05). Knockdown of LOX in 231-OE6 cells attenuated the increased migration and invasion. Conversely, overexpression of LOX in 231-KD2 cells rescued the decreased migration and invasion(P<0.05). Conclusion: The expression of LOX is up-regulated by Osx in human breast cancer cells, and it promotes the migration and invasion of breast cancer cells.