Abstract: The oxidation environment under different working condition in the primary loop of nuclear power plant is one of the main reasons for resin failure in the cleanup bed.According to some outstanding problems of current primary loop purification bed resin of nuclear power plant, including short service life and bad antioxidant properties, the performance of different resins were compared through a lot of experiments. Combined with system test on factory site, the purification bed resin-more suitable for primary loop use-is screened out, which has a longer service life, high cross-linking degree and better oxidation resistance performance.