Abstract: Snake-cage resin is a kind of amphoteric resin with special structure.Because of its unique retardation ability and its advantage of water regeneration it has been used in many ion separation processes.In this article, the author described the structure of snake-cage resin and the mechanism of ion retardation proposed a new concept, ion retardation capacity, to estimate the snake-cage resins.Then the determination of residual anion exchange capacity, residual cation exchange capacity, total anion exchange capacity, ion retardation capacity and total cation exchange capacity were studied.Finally, the determination of these capacities for Retardion 11A-8 and nine other snake-cage resins synthesized by the author was carried out.

Key words: Snake-cage resin, Ion retardation, Residual ion exchange capacities, Ion retardation exchange capacity