Nitrogen-doped　titanium　dioxide　(N-TiO2)　nanopowders　were　prepared　by　hydrothermal　synthesis　in　H2SO4,　HCl,　HNO3　using　the　titanium　nitride　(TiN)　as　both　titanium　resource　and　nitrogen　resource.　Effects　of　solvent　medium　and　hydrothermal　temperature　on　the　crystalline　type,　morphology,　size　and　the　photocatalytic　activities　of　the　product　was　investigated.　The　SEM,　XRD　result　shows　that　granular　anatase　TiO2　was　obtained　in　H2SO4,　while　rod-like　rutile　TiO2　could　be　obtained　in　HCl　and　HNO3,　the　crystalline　size　was　as　follows:　d(HCl)　＞d(HNO3)＞d(H2SO4),　it　largens　with　increasing　hydrothermal　temperature　in　the　same　solvent　medium.　Nitrogen　atoms　are　doped　into　TiO2　lattice,　form　a　new　bond　of　O-Ti-N　resulting　in　an　increase　of　the　lattice　distance,　which　are　confirmed　by　XPS,　HRTEM.　The　narrow　of　band-gap　and　the　visible-light　response　are　due　to　nitrogen　doping,　which　are　shown　by　UV-Vis　spectra　analysis.　The　experiments　of　photodegradation　of　methyl　orange　show　that,　the　photocatalytic　activities　was　as　follows:　η(H2SO4)＞η(HNO3)＞η(HCl),　it　lessens　with　increasing　hydrothermal　temperature　in　the　same　solvent　medium.　©,　2015,　Journal　of　Functional　Materials.　All　right　reserved.