Under different conditions，such as different solvents，temperature，．reaction time，the amount of reactants and order of addition，the chloromethylated polystyrene were reacted with butyl lithium；the products without cross—linking were selected for the preparation of graft copolymers．Besides，the chloromethylated polystyrene was allowed to react with methyl methacrylate in the presence of lithium．Neither polymethyl methacrylate nor polymethyl methacrylate-grafted copolymer could be isolated by the reaction of polystyrene methylene lithium prepared in ether soluti6n with methyl methacrylate．However，the polymethyl methacrylate-grafted copolymer was isolated by the reaction of methyl methacrylate with polystyrene methylene lithium pre-pared in toluene solution．The graft copolymer was identified by the quantitative analysis of carbon，hydrogen，and chlorine，the determination of exchange capacity of the hydrolyzing product，the turbidimetric titration，and infra-red absorption spectra．The percentage by weight of polymethyl methacrylate in the graft copolymer was about firty as estimated by the first tWO methods mentioned above．Graft copolymers were isolated by the reactions of chloromethylated polystyrene with methyl methacrylate in the presence of metallic lithium．The percentage of polymethyl methacrylate in the graft copolymers was about three to three and half．The graft copoly-mers were identified by the determination of exchange capacities of the hydrolyzing pro-ducts．the turbidimetric titration and thermo—mechanical properties．