Photocatalysis　provides　a　sustainable　route　to　convert　N-2　to　NH3　with　the　aid　of　a　photogenerated　electron.　Beyond　the　typical　issue　in　the　photocatalytic　field,　NH3　synthesis　requires　adsorption,　activation,　and　hydrogenation　of　N-2.　In　this　report,　Ni-doped　TiO2　(Ni-x-TiO2)　photocatalysts　were　fabricated　by　a　simple　sol-gel　method　to　introduce　the　oxygen　defects　and　Ni　site　on　TiO2.　The　oxygen　vacancy　(Vo)　enhances　the　adsorption　of　N-2　on　the　catalyst　surface.　The　Ni　doping　induced　a　defect　energy　level　below　the　conduction　band,　which　prefers　to　accept　the　photogenerated　electron.　The　electron　captured　by　Vo　tends　to　transfer　to　the　adsorbed　N-2　and　activate　N-2.　On　the　other　hand,　the　Ni　site　is　a　typical　H-2　production　site.　It　provides　enough　H-2　for　the　hydrogenation　of　N-2　to　form　NH3.　To　sum　up　all　of　these　advantages,　Ni-doped　TiO2　displays　a　high　NH3　production　rate　of　46.80　mu　mol.g(-1).h(-1)　which　is　about　7　times　higher　than　that　of　pure　TiO2.　This　manuscript　provides　a　potential　method　to　design　a　highly　efficient　photocatalyst　for　the　NH3　synthesis.