Copolymer beads prepared from styrene and divinylbellzene were chloromethylated by a mixture of sulphuryl chloride-methylal．The chlorine contents of the ehlorome-thylated copolymer beads tire found to be 16—17％ while the exchange capacities of the strong basic type anion．exchange resin obtained thereof arc within the range of 3.3-3.5 meq／g (dry resin)．The effects of the molar ratio of the raw materials，the amount of zinc chloride catalyst．and the contents of methanol and water in methylal on the ehlorine contents of the ehloromethylated eopolymer beads and exchange capacities of the synthetic strong basic type anion-exchange resin were investigated．In contrast with the traditional chloro methyl methyl ether method better results were obtained by using lower molar ratio of the raw materials and less amount of the catalyst．Methanol and water contents of methylal if present within certain limits have little or no effect on the chlorine content of the beads and exchange capacity of the resin．