To study the effects of ELAC2 on the invasion, migration and radio-sensitivity of human breast cancer cell MCF-7, ELAC2 genes were transfected into MCF-7 using Lipofectamine transfection assay. Western blot assay was used to detect the protein expression of ELAC2, cyclinB, CDC2 and P53 while wound healing assay and Boyden chamber assay were performed to determine cell invasion and migration, and colony formation assay and flow cytometry assay were used to detect cell surviving fraction and cell cycle. The results show that MCF-7/ELAC2 cell lines with overpression of ELAC2 were successfully established. The overexpression of ELAC2 could obviously inhibit invasion and migration of MCF-7 cells. The overexpression of ELAC2 enhanced the radiosensitivity of MCF-7 cells after x-ray exposure and caused increased ratio of G2 phase. At the same time cyclinB protein expression decreased and the expressions of P53 and Tyr-15 phosphorylated CDC2 up-regulated. The results suggest that the overexpression of ELAC2 may obviously inhibit invasion and migration of MCF-7 cells, and may result in radiosensitivity enhancement of MCF-7 cells to X ray, which could be associated with either down-regulation of protein expression of cyclinB or up-regulations of protein P53 and Tyr-15 phosphorylated CDC2.