Fenton like oxidation method was used in this research to decompose the cationic and anionic resins. Acid digestion and fenton method was also studied to compare the results. Acid digestion and fenton methods did not show desirable results, so the research was focused on fenton like process. For this purpose the Cu2+ was used as catalyst and H2O2 as oxidant. Five parameter including temperature, pH, Cu2+ concentration, H2O2 addition flow rate and time were studied to obtain the optimum value for decomposition of fresh resin. It was found out that the optimum values was as: temperature:75 C, Cu2+ concentration:0.3 M, H2O2 addition flowrate:0.5 ml/min for cationic and 0.25 ml/min for anionic resin and time: 2 hours. By optimization of the parameters decomposition weight percent of 88% was obtained for cationic resin and 83% for anionic resin. The optimum condition was applied for real sample which was a mix of cationic and anionic resin from Tehran research reactor. The decomposition percent of 81% was achieved. The resins was characterized before and after decomposition by FTIR and SEM which showed the decomposition. COD analysis showed that only 2% of decomposed resin maintained in the solution and 98% was converted to CO2 and H2O.