Tungsten oxide nanopowder, which may be applied for preparing window heat insulation film, has photochromic properties. This kind of heat insulation film of tungsten oxide is very thin with the characteristics of good heat insulation effect and high visible light transmittance. And it does not affect indoor lighting. Besides, it is anti-glare. Nano grain size tungsten oxide is an important semiconductor material that has broad application prospects in information storage, fuel cells and chemical sensors, etc. Nano grain size tungsten…