Abstract: The freeze-concentration method is a water treatment method that achieves the concentration and separation of substances under low-temperature conditions based on the principle of solid-liquid phase equilibrium in physical chemistry. Radioactive wastewater containing volatile nuclides is extremely harmful to human health, and it is of great significance to study feasible treatment methods. In this paper, the freeze-concentration method was used to treat the iodine-containing simulated solution, and a treatment process model was proposed. It was deduced that there was an inverse relationship between the decontamination factor(DF) and the volume reduction factor(V_RF) for the solution at a specific freezing temperature and concentration. The factors that influence the treatment effect were studied, and the feasibility of applying this method in engineering was discussed. The results show that the reduction of nuclide concentration leads to an increase in the DF, which has little effect on the V_RF. Increasing the freezing temperature leads to a rise in the DF and a decrease in the V_RF. By using a multi-stage freeze-concentration method, the processing efficiency can be effectively improved. A three-stage freezing concentration treatment was carried out at −6 ℃ for the simulated solution containing I⁻ mass concentration of 0.100 g/L. The results show that the DF is 108.69±9.80, the V_RF is 5.81±0.48 and no secondary waste is generated. This method provides a new approach for treating radioactive waste containing volatile nuclides.