The purpose of this study was to evaluate the cytotoxicity of nanometer magnetic composite via being cultured with osteoblast-like cells (MG-63). The osteoblast-like cell (MG-63) was utilized as the seed cell. The cells were cultured on the surface of nanometer magnetic composite. After union culturing, on the day 1, 3, 5, 7, the cytotoxicity of nanometer magnetic composite was evaluated by MTT method and the cell morphology was observed by SEM. Meanwhile, on the day 4, 7, 10, the alkaline phosphatase (ALP) activity was tested respectively. These results demonstrated that the typical cell morphology could be observed when the osteoblast-like cells were cultured on nanometer magnetic composite substrate in vitro. Cell proliferation and ALP activity became higher as the prolongation of cultivate time in the group of nanometer magnetic composite. The study showed that nanometer magnetic composite had a little inhibition to cell proliferation and ALP activity in vitro cell culture, as compared with the chitin and PLA fiber substrate. So the feasibility of nanometer magnetic composite as scaffold for bone tissue engineering should be studied further.