The separation characteristics of the carboxymethylcellulose(CMC) membrane for organic aqueous solution were determined by vacuum pervaporation. The apparatus used in this experiment can forecast the concentration distribution and/or permeating phenomenon of organic solvent in the membrane, unlike the conventional apparatus. The purpose of this study is to investigate the permeation and separation characteristics of the homologous series of organic solvents through selected hydrophilic polymer membranes. CMC membrane is suitable for the separation of water/organic solvent mixtures due to the high separation factor and the large amount of permeation. The separation analysis was carried out with a Hewlett Packard, HP5890 Series Gas Chromatograph. The permeating concentration is generally increased at the beginning stage, but led to equilibrium permeate according to experiment time. It is desirable that the separation characteristics should be evaluated of equilibrium state.