Abstract: NF 3,a novel polyamide composite membrane fabricated by a new method, has a functional layer that has a dense cuticle and a loose endothecium instantaneously, therefore it has a high flux and a special selectivity. It can separate different inorganic salts and organics on the basis of their nuances of their bulk other than the exclusion between the charges. It is also found that the working conditions have perceptible effects on its selectivity. What's more, the possibility is validated that NF 3 can be applied in the industrial of dye.