Photocatalyst can produce more than 99% of the results of resolving to formaldehyde and organic matter under the visible light, and because this course adopts contacting--the catalysis& oxidation principle, the catalyst composition plays a medium role, therefore the photocatalyst composition have no change, so does not need any treatment for using a long time. photocatalyst filter net's main raw material: foamed metal, photocatalyst ,and nickel etc. Utility function that the world initiates: Can water-wash , the effect after water-washing has no degradation. Scope of application: places where we can use filter screen such as air conditioner , the filter ,etc.