nake-cage resin has the ability of ion retardation and can be regenerated by water as an eluant.It can be specially used in the separation of different electrolytes and deionization of non-electrolytes in concentrated solutions.In this article several snakecage resins containing weak acidic and strong basic groups were synthesized.The effect of crosslinking degree of the cage resin on ion retardation capacity and ion separation ability were studied.These snake-cage resins were used in removing the water soluble nonvolatile impurities from the spinning bath solution.sodium thiocyanate of polyacrylonitrile.Some of them showed satisfactory results.