Nitrogen-doped TiO2 was prepared by Ti(SO4)2 solution reacting with NH3 aqueous solution. The optical absorption edge of nitrogen-doped TiO2 shifted 20 nm toward the infrared and also absorbs the visible light from 400 nm to 530 nm compared with undoped TiO2.Band gap of undoped TiO2 was 3.24 eV and nitrogen-doped TiO2 was 3.14 eV. X-ray photoelectron spectroscopy(XPS) measurements show that the nitrogen in N-doped TiO2 is in dissociative interstitial state. That the new absorption band at 400 nm ~530 nm is induced by oxygen vacancies in N-doped TiO2, which exhibits a narrow band close to the conduction band. The MTT assay was used for detecting the activity of N-doped TiO2 on the growth of leukemic HL60 in vitro. The results indicate that N-doped TiO2 can improve the efficiency of destructing leukemic HL60 cells no matter there is or not visible-light irradiation.