N-doped nano-TiO2 was obtained by calcining in N2 the precursors prepared by the sol-gel method. The N-doped nano-TiO2 was characterized by XRD, XPS, TEM and ultraviolet-visible light spectrometry. The influence of environment atmosphere, calcining temperature and duration on the crystal phase, average crystal diameter, adsorption wave length, contents of surface O, N of N-doped nano-TiO2 were studied and compared with that of TiO2 prepared by the same method and under same conditions but calcined in the air. Results showed that N-doped nano-TiO2 has a higher phase transition temperature, higher contents of surface O, higher contents of interstitial N, smaller average crystal size and longer adsorption wave length, which is 435 nm for the sample calcined in N2 for 4 hours at 550 ℃.