Different from many works which focus on doping to improve the visible light absorption and the photocatalytic activity of TiO 2 , this work finds that the N-doped rutile TiO 2 nano-rods have tunable photocatalytic selectivity. This finding was confirmed by the photo-degradation of azo dyes. Results reveal that pure rutile TiO 2 mainly exhibit no selectivity in the photocatalytic degradation of a methylene blue and methyl orange (MO) mixed solution, whereas N-doped rutile TiO 2 exhibits photocatalytic selectivity for MO. N doping has been shown to greatly change the surface state than the energy band structure of TiO 2 . In a deeper analysis, some doped N atoms replace surface saturated O 3c on the {110} facets of rutile TiO 2 and act as unsaturated N 3c , which enhances adsorbent selectivity and relevant photocatalytic activity of MO. This research hopes that by providing a deeper understanding of non-metal doping in TiO 2 , a new strategy for photocatalytic selectivity can be developed.