With the fast developing nanotechnology, questions are being raised about the potential toxic effects of the nanomaterials on human health. The effects of lanthanum oxide nanoparticles on the primary osteoblasts are investigated in the present study. As an indicator of membrane damage, lactate dehydrogenase is quantitatively assessed. The quantitative analysis on cellular uptake of lanthanum oxide nanoparticles could be detected by flow cytometer and inductively coupled plasma mass spectrometry respectively. The results demonstrate that lanthanum oxide nanoparticles can enter cells through cell membrane and the nanoparticles taken up by the cells followed dose and time dependent effect. The method could be used for the initial screening of the uptake potential of nanoparticles as an index of nanotoxicity.