Abstract: Two types of gel cation resins with different cross-linking degrees（16% and 8%） are studied for the nuclear grade resin type selection in CAP（China Advanced Pressurized Water Reactor） series of Generation III nuclear power plants. The effect of different resin specifications on operation performance is evaluated by means of dynamic simulated experiments. Results show that the monosphere resin with higher cross-linking degree（e.g. 16%） has an advantage in respect of decontamination, operation life span, differential pressure and economical efficiency. So resin of high cross-linking degree is recommended for the ion exchange design in the liquid radwaste system of CAP series plants.