Abstract: In order to achieve the goal of unrestricted opening after the decommissioning of city radioactive waste storage vaults, the key problems of radiation impact assessment of the decommission of waste storage vaults were discussed and the radiation impact of personnel and surrounding environment was evaluated in this paper. The polluted area was determined by comparing the source investigation with the implemented control limits. Combined with the background level of local radiation environment and operation history, the pollution causes were analyzed. According to the decommissioning implementation scheme, the production amount of radioactive wastes and the activity level before servicing were obtained. Empirical formulas were used to estimate the external and internal radiation doses of professional personnel, and the public radiation impact was analyzed. The formulation of control limits and the acceptable level of ²²⁶Ra in the soil of the decommissioning site were discussed. The radioactive indexes for decommissioning implementation and the suitable sites control limits were selected. The specific measures to minimize waste in decommissioning construction were put forward. The maximum individual dose of decommissioning implementation was 3.9 mSv, which was lower than the dose constraint value 5 mSv. The measured dose was about 2 orders of magnitude lower than the evaluation value. The professional personnel dose in the decommissioning activities met the requirements of the national standard, and the radiation impact of decommissioning was within an acceptable range.