Utilizing the unique fibril-nod feature of PTFE membrane, smooth surface, chemical stability, heat-resistance, flame-retardant property, anti-ageing, the hydrophobic properies to achieve the high filter efficiency, the filter effectiveness of air filter bag made from PTFE pore membrane can reach as high as 99.99%, equal to zero exhaust with the low running resistance, quick filter speed, long using time and low running cost. It is mainly used in the fume filter of various industrial kilns such as the chemical, iron and steel, power generation, cenent, refuse incineration etc. air purificaton in the pharmaceutical.