The invention discloses a preparation method of blue tungsten oxide nanowires. At present, preparation methods of tungsten oxide nanowires mainly include hydrothermal process, thermal evaporation, sol-gel process and chemical vapor deposition process. Although the preparation methods of the tungsten oxide nanowires have been reported, the preparation methods are complex in most cases, troublesomein process and high in cost. The preparation method includes: adopting tungsten sulfide (WS2) solid-state powder as a tungsten source and water vapor as a reductant-oxidant, and adopting a CVD processto prepare the blue tungsten oxide nanowires. Water vapor high-temperature oxidized tungsten sulfide powder is adopted to prepare the blue tungsten oxide nanowires, so that the preparation method issimple, and the blue tungsten oxide nanowires are uniform in diameter distribution and high in crystal quality.