To get the more chloromethyl groups than copolymerized styrene and chloromethylstryene(CMS), polystyrene was directly chloromethylated with chloromethylether and zinc chloried. The optimum reaction condition for making the polychloromethylstyrene was the duration of 8 hours and the temperature of 4$0^{circ}C$. polychloromethylstyrene was reacted with trimethylamine, pyridine, dimethylsulfide and triethylphosphite. To modify the properties of polyacrylonitrile, acrylonitrile (AN) monomer was copolymerized with various mole percentage of chloromethyl-styrene and AN-CMS copolymer was reacted with trimethylamine. The inherent viscosity of ammonium salt of AN-CMS copolymer was increased in proportion to the mole percentage of quaternary ammonium salt. The moisture regain of ammonium salt of AN-CMS copolymer was increased in proportion to the mole percentage of quaternary ammonium salt. The anti-static property was consicuously improved in comparison with that of AN homopolymer. The tensile strength was decreased slightly.