Objective:To evaluate the radiosensitivity enhancement effect of FePd@CNTs nanocomposites on human breast cancer MCF-7 cells.Methods:FePd@CNTs nanocomposites were synthesized by chemical reduction method. Transmission electron microscope and energy dispersive spectrometer were utilized to characterize the surface morphology and chemical composition of FePd@CNTs nanocomposites. The compatibility of FePd@CNTs nanocomposites with human normal breast epithelial MCF-10A cells was determined by CCK-8 assay. The radiosensitivity enhancement effect of FePd@CNTs nanocomposites on MCF-7 cells was assessed by CCK-8 assay, flow cytometry and clony formation assay.Results:FePd nanospheres were successfully modified on the surface of CNTs by chemical reduction method. FePd@CNTs nanocomposites showed a low toxicity to MCF-10A cells (IC 50=738.3 μg/m), and effectively enhanced the effect of X-ray radiation on MCF-7 cells (sensibilization ratio=1.22). Conclusion:FePd@CNTs nanocomposites exhibit a promising potential for treating breast cancer and enhancing radiosensitivity effect.