A hot wire anemometer utilizing metal-coated carbon naonotube wire includes a detecting element, a signal enlarging element, a signal dealing element, and a display device. The hot wire of the detecting element includes a nanotube composite wire. The carbon nanotube composite wire includes a carbon nanotube wire and a metal layer. The carbon nanotube wire includes a plurality of carbon nanotubes spirally arranged along an axial direction of the carbon nanotube wire. The diameter of the carbon nanotube wire ranges from 50 nanometers to 30 micrometers. The rate of twist of the carbon nanotube wire ranges from 250 t/cm to 300 t/cm. The metal layer is coated on a surface of the carbon nanotube wire. The thickness of the metal layer ranges from 50 nanometers to 5 micrometers.