Poly(4-nitrostyrene) was synthesised by nitration of polystyrene and poly(3-ni-trostyrene) was synthesized by free radical bulk polymerization of 3-nitrostyrene. Polyaminostyrene(PAS) was synthesized by reduction of polynitrostyrene. Composite reverse osmosis(RO) membranes were fabricated via interfacial polycondensation of PAS and trimesoyl chloride(TMC) on the polysulfone support membrane surface. As the RO properties, salt rejection of poly(3-aminostyrene)(mPAS) membrane was better than poly(4-aminostyrene) (pPAS), but vice versa for permeate flux. The blend of 1, 3-phenylene diamine(mPDA) monomer in PAS reaction solution increased the salt rejection and the blend of acyl halide monomer in TMC reaction solution increased the permeate flux. The RO performance of mPAS and pPAS, in which various composition of the blended solutions were added, was found to be not much different. In particular, the PAS composite membrane which was prepared by interfacial polymerization of PAS/mPDA(70/30) blend solution and TMC/benzoyl chloride(80/20) blend solution showed a permeate flux of up to 1.0$ell$/$m^2$.hr.atm and a salt rejection of over 90%.