离子交换树脂是一种由有机分子单体聚合而成的，具有三维网络结构的多孔海绵状高分子化合物。在构成网络的主链上有许多活动的化学功能团，这些功能团由带电荷的固定离子和以离子键与固定离子相结合的反离子所组成。树脂吸水膨胀后，化学功能团上结合的反离子与水中的离子进行交换。
Ion exchange resin is a porous spongy polymer with three-dimensional network structure, which is synthesized from organic monomers. There are many active chemical functional groups in the main chain of the network. These functional groups are composed of charged fixed ions and counterions combined with ion bonds and fixed ions. After the resin is absorbed and expanded, the ions bound on the chemical functional groups are exchanged with the ions in water.