The preparation of conducting water soluble sulfonated polyaniline, poly (3-amino-4-methoxybenzenesulfonic acid), has been investigated. Poly (3-amino-4-methoxybenzenesulfonic acid) has been polymerized via chemical oxidation. Using a dialysis membrane, separation and purification of high molecular weight polymer from low molecular oligomers were carried out successfully. UV-Visible spectroscopy, cyclic voltammetry and four-point-probe conductivity measurements of polymer were recorded. The prepared polymer was conducting and fully water soluble. The conductivity of polymer was about 0.0430-0.75S/cm and it were found that reaction temperature, monomer and oxidant concentration had dramatic effect on conductivity of poly(3-amino-4-methoxybenzenesulfonic acid).