Porous poly(chloromethyl styrene) (PCMS) resins were synthesized by suspension polymerization. The cationic resins having quaternary ammonium groups were prepared by the reaction of the synthesized resins with tertiary amines. The effects of the content of the crosslinking agent and diluent on the structure and characteristics of the resins were investigated. It was found that density, water content, and ion-exchange capacity of resins were increased with the decrease of crosslinking agent and with the increase of diluent content. whereas the fixed charge density was decreased. The reactivity of resins with amines increased with the decrease of length of the alkyl chains, and then ion-exchange capacity increased as well. The sorption behaviour of the cationic resins was also investigated by using the sodium salt.