Polysulfone ultrafiltration membrane was coated with polyisobutylene(PIB) as a top layer to separate chlorinated hydrocarbons. The solubility parameter differences between PIB, water and perchloroethylene(PCE) or trichloroethylene(TCE) show that the solubility parameter difference between PIB and TCE or PCE is similar while that between PIB and water is far less, indicating that PIB is selective to chlorinated hydrocarbons. The pervaporation separation of TCE and PCE shows that TCE is concentrated more than four times, by PIB composite membrane, while PCE is concentrated more than thirteen times. This result shows that PIB composite membrane in this study seems to be an appropriate selective layer for the separation of TCE and PCE from aqueous organic solutions.