Charged mosaic membrane (CMM) consists of parallel domains of anion-exchange and cation-exchange elements,which are very helpful for separating the organics from salt solutions [1].Many attempts have been reported to prepare charged mosaic membranes by chemical modifications of multiblock copolymers [2],laser-induced graft polymerization [3],polymer blends [4],hybrid membranes [5] and laminated structures [6].Most of these processes were quite complicated and the lower flux because the membranes were thick in general.Based on our early studies [7],the object of this paper was to optimize the preparation conditions of the CMM.