In this research, polyvinylchloride/ styrene-butadiene-rubber blend heterogeneous cation exchange membranes were prepared by solution casting technique using tetrahydrofuran as solvent and cation exchange resin powder as functional groups agent. Poly methyl methacrylate (PMMA) was also employed as membrane surface modifier by emulsion polymerization technique to improve the membrane selectivity and anti-fouling property. The effect of used emulsion composition on properties of home-made membranes was studied. SOM images showed uniform particles distribution and relatively uniform surfaces for the membranes. Results revealed that surface modification of membrane led to decrease in water content, ion exchange capacity, and ionic permeability in composite membranes. Membrane potential, transport number, selectivity, ionic concentration, and membrane surface electrical resistance all were increased by the PMMA coating on membrane surface. Also, the results showed that decrease of (Methyl methacrylate (MMA): Sodium dodecyl benzene solfanate (SDBS)) ratio in used emulsion during the modification process led to decrease in water content, IEC and permeability in composite membranes. Conversely, opposite trends were found for membrane potential, transport number, selectivity, and electrical resistance by (MMA: SDBS) ratio decreasing in used emulsion. Composite membranes exhibited higher potential, selectivity, transport number, and permeability for monovalent ions compared to bivalent ones. Modified membranes showed good ability in (monovalent/bivalent) ions separation.