alpha-Fe/FeTiO3/TiO2 was synthesized through the reduction of Fe3O4@TiO2 at 800 degrees C, and subsequently nitrided in NH3 atmosphere at the nitridation temperature T-N = 400, 600, 800 and 1000 degrees C. In the crystal lattice of TiO2, with increasing T-N, the N element itself exhibits the chemical states of TiO2-xNx, TiN and interstitial N, and simultaneously it induces the complex variation of the chemical state of the Ti and O elements. The photo catalytic performance of the nitrided samples is not determined only by the chemical states of the N element but by the synergistic effects of chemical states of the N, Ti and O elements.