Au　decorated　TiO2　nanotubes　array　was　successfully　fabricated　on　a　Ti-Au　alloy　via　an　electrochemical　anodization　process.　The　crystal　phase　and　microstructure　of　the　TiO2　nanotubes　array　were　characterized　by　X-ray　diffraction　(XRD),　field　emission　scanning　electron　microscopy　(FESEM)　and　transmission　electron　microscopy　(TEM),　respectively.　Au　particles　were　well　distributed　among　TiO2　nanotubes　and　acted　as　the　catalyst.　It　was　found　that　the　sensor　based　on　Ti-Au　alloy　anodization　can　be　a　promising　sensor　which　was　highly　sensitive　to　low　concentrations　of　nitrogen　dioxide　(NO2),　and　response　at　room　temperature.　The　sensitivity　of　Au-decorated　TiO2　nanotubes　sensor　was　36.11　to　8　ppm　NO2　at　room　temperature.　Meanwhile,　the　resistance　signal　of　Au-decorated　TiO2　sensor　changes　quickly　within　80　s　upon　exposure　to　8　ppm　NO2　at　35　degrees　C,　the　undecorated　TiO2　however　takes　much　more　time　(＞　110　s)　to　respond　and　the　resistance　signal　remains　unstable.