Abstract: Five reactor primary loop structural materials were subjected to immersion corrosion test by three-step chemical decontamination method at 95 ℃. The electrochemical performance of the materials in the decontamination solution and the compatibility of both were studied, and oxide film was prefabricated on 06Cr18Ni11Ti austenitic stainless steel to verify the effect of the three-step chemical decontamination method. The results show that the corrosion rates of five materials all met the requirements, and the mass loss and corrosion rate of 0Cr17Ni4Cu4Nb martensitic stainless steel were significantly higher than those of 06Cr18Ni11Ti, 06Cr19Ni10N austenitic stainless steels and 00Cr30Ni59Fe10, 00Cr25Ni35AlTi nickel based alloys. The material corrosion was mainly caused by oxalic acid citrate solution. There was no pitting corrosion and intergranular corrosion among the five experimental materials after immersion test. The three-step chemical decontamination process had a good removal effect on the surface oxides of 06Cr18Ni11Ti austenitic stainless steel.