Integrally skinned polyetherimide(PEI)asymmetric membranes were prepared by the phase inversion process in which the casting solution contained dimethylacetamide (DMAc) as a solvent and PVP as a additives.The performance of membranes was characterized by nanofiltration of Rose Bengal (MW 1017.64 Da) and Methylene blue (MW 373.91 Da) dyes in ethanol.Rejection values of 97 % and 94.5 % were achieved for Rose Bengal and Methylene blue at a transmembrane pressure 100 psi.Moreover,the solvent flux and solute rejection of membranes were tested after soaking membranes in ethanol,isopropyl alcohol,n-hexane and CCl4 respectively.A really retention stable membrane was obtained from the study compared to commercial membranes such as MPF-34,MPF-44,StarMem 240 and Solsep(010706).And in the study of long time stable of membranes,our membrane kept an excellent stable on its flux and rejection.Swelling experiment showed that the swelling degree of our membrane was far lower than those of commercial membranes.The relationship between pressures and the solvent flux and solute rejection of the membrane were studied using the M4 membrane up to a pressure of 100-600 psi.The cross section of membranes was characterized using scanning electron microscopy.