Abstract: The biological behavior of magnetic nanoparticles with diameter of 10 nm on human liver cancer line SMMC7721 and human normal liver cell line HL7702 in vitro was studied.Both cells were cultured in the media containing Fe₃O₄ nanoparticles.Inverted microscopy and transmission electron microscopy（TEM） were used to investigate the morphologies of cells and the nanoparticles distribution in the cells;CCK-8 assay was used to evaluate the effects of the nanoparticls on the proliferation of cells.According to inverted microscopy and TEM analysis,the nanoparticle-exposed cells are normal in morphologies after 72h.The nanoparticles can enter the cytoplasm and distribut in the phagosome and phagolysosome.The result of CCK-8 array show the naoparticle has no significant effect on cells proliferation.This study provides detailed data for the effect of magnetic nanoparticles on liver cancer cell.It also offers valuable data for the further application of magnetic nanoparticles in tumor hyperthermia.