The purpose of this study was to examine the changes of cancer cell in ultrastructure after inorganic crystal nanoparticles (ICN) absorption. HAP and TiO2 nanoparticles were incubated with the Bel- 7402cells for 1 h and 8 h respectively. Then, cancer cells were collected and examined under transmission electron microscope (TEM). In cytoplasm, nanoparticle were contained in some vacuoles. Some death features of cell appear. The experimental results indicated that ICN can induce cancer cells death.