Cellulose triacetate (CTA) hollow fiber membrane for reverse osmosis (RO) desalination of brackish water with high salinity has been modified for pervaporation (PV) membrane of separating organic/organic mixture. The experiments presented that modified performance of CTA hollow fiber membrane treated by the organic solvent was affected by the modifying conditions. PV performance of CTA hollow fiber membrane modified mainly depends on the concentration of the modifying agent and the treatment time of CTA hollow fiber membrane in the aqueous acetone. The results showed that the membrane treated respectively by 5% acetone aqueous solution possesses a good PV separation performance, i.e. the separation factor 1998 and the permeate flux 45.1 (g/m(2).h). It was exhibited from scanning electron microscope (SEM) photograph were produced. The structural changes from porous, defect to non-porous, even on the membrane surface and turn from asymmetric membrane of two layers consisting of the active and the support into the homogeneous membrane of single layer in the cross section of the membrane would indicated why the original RO membrane can become that of PV by means of modification treatment.