Abstract: In order to solve the problems with the continuous decay pools in the nuclear medicine department of a hospital, such as the unreasonable structure, the large dead water area and the failure to make the radionuclides effectively stay in the continuous decay pools of radioactive wastewater, which results in substandard discharge of radioactive waste water, the study of the continuous decay pools was carried out. Three-dimensional fluid simulation software was used to simulate and analyze the water flow regularity, nuclide concentration distribution and dead water volume of the continuous decay pools. After simulation analysis, an optimized structure type of the continuous decay pools is proposed that could meet the emission standards. The results show that the activity concentration of radioactive waste water at the discharge port of the continuous decay pools can be lower than 10 Bq/L, by adopting structural optimization measures such as diagonal drainage, adding baffle and baffle holes, and setting different angle chambering at the bottom of the continuous decay pools, and finally the standard discharge can be achieved. The research results can provide reference for the treatment of radioactive waste water in the future.