This membrane is our invention patent products,it is Inner-pressurized type hollow fibre UF membrane with single skin layer of modified PAN. (1) PAN's hydrophily and anti-fouling behavior can be improved through adding inorganic salts and organics to PAN material. (2) The inner pressurized type UF membrane with single skin layer was prepared with delaying gelatum spinning technique by intelligent control. In the course of membrane separation, the resistance of the membrane with single skin layer structure is smaller than that of the membrane with double skin layer structure; the operating pressure can be lower; furthermore, as far as the recovery of membrane's flux after back-washing is concerned, the former is easier than the latter.