Ultrafiltration is a perforated membrane separation performance depends on the size of the hole, uniformity and distribution, so the relationship with the structure of the membrane material closely than other films. Of course, depends on the film formation process, the structure of the material also plays a certain role. On the other hand, as the polyimide ultrafiltration membrane material is mainly to meet the organic matter, radioactivity and temperature requirements of the medium. General polymer ultrafiltration membrane material is mainly to meet the organic matter, radioactivity and temperature requirements of the medium. General polymer ultrafiltration membrane can only be used at 100 ℃ and lower temperatures. At the same time it is difficult for the separation of organic matter, such as fuel oil filter, heat vegetable oil circulation and separation. Having high thermal stability, mechanical and chemical stability of the polyimide is one suitable material. But the main limitation of the polyimide again a high melting point and low solubility of the film-forming process is complicated. By the acid-soluble polyamide film is required to heat or chemical imidization so difficult to control the structure of the film, although this work is rarely seen, but it is an area worth exploring. Because this method is not limited in structure, it can be the most resistant to organic polyimide film.