Novel charge-mosaic composite membranes composed of cation and anion permeable domains were prepared. Poly(4-methylstyrene-isoprene-styrene-isoprene-4-methylstyrene) pentablock copolymer (MsISIMs), poly(isoprene-4-methylstyrene) diblock copolymer (IMs), and poly(isoprene-styrene-isoprene) triblock copolymer (ISI), used as the precursor of the charge-mosaic membranes, were polymerized from styrene (S), isoprene (I), and 4-methylstyrene (Ms). MsISIMs and a blend of ISI and IMs were then dissolved in benzene and cast on a polypropylene microporous supporting membrane. After chemical modification, the MsISIMs and IMs/ISI charge-mosaic composite membranes were obtained. Our experimental results show that the IMs/ISI charge-mosaic composite membrane is similar in membrane structure and properties to the MsISIMs charge-mosaic composite membrane.