In　this　work,　a　distinctive　hierarchical　tree-like　rutile　TiO2　architecture　growing　directly　on　the　conductive　surface　of　indium　tin　oxide　(ITO)　conductive　glass　substrates　was　successfully　prepared　via　a　facile　one-step　hydrothermal　process,　where　titanium　butoxide　used　as　Ti　source　and　HCl　as　an　acidic　medium　solution.　The　as-obtained　products　were　characterized　by　X-ray　diffraction　(XRD),　field　emission　scanning　electron　microscopy　(FE-SEM),　transmission　electron　microscopy　(TEM),　selected　area　electron　diffraction　(SAED)　and　applied　in　gas　sensor.　The　characterization　of　FE-SEM　indicates　that　the　morphology　of　the　products　can　be　controlled　by　regulating　solution　acidity,　the　amount　of　titanium　butoxide,　reaction　time,　addition　agents,　and　so　on.　The　gas　sensing　test　shows　that　the　sensor　fabricated　with　3D　nanotree-like　rutile　TiO2　has　higher　gas　response　towards　CH3COCH3　gas　than　those　with　1D　rod-like　TiO2　or　common　TiO2　precipitate,　indicating　that　the　3D　nanotree-like　architectures　may　be　promising　gas　sensitive　materials.