Abstract: TiO₂ precursor was prepared by Ti（SO₄）₂ solution reacting with 28% NH₃ aqueous solution. Nitrogen-doped TiO₂ was obtained by calcinating the preciusor in different conditions. Its optical ab- sorption property and morphological structure were studied. The results show the sample calcinated at 400℃ for 1h is anatase and the average particle size is about 15nm. Its optical absorption edge shifts 22nm toward the infrared and it also absorbs visible light from 400nm to 510nm compared with undoped TiO₂.The decomposition of methyl orange solution under visible light reveals nitrogen-doped TiO₂ has visible light activity.