The lifting-turnover mechanism is the key equipment of the post-processing system of the strong-radiation rod. According to the relevant design specifications, it is necessary to ensure that the rods does not break under seismic conditions and that the safety function and running performance of the mechanism are normal. To verify the seismic performance of the mechanism, based on ANASYS Workbench, finite element models of the lifting-turnover mechanism containing a hoist, a steel-wire rope, a silo rack-silo part, a rolling-over vehicle and upper/lower rails in the post-processing system, are established for seismic evaluation. Then, the stress assessment and strength check of the main units and the major bolts are carried out according to ASME codes, and the number of bolts installed on the upper rail is optimized. The simulation results show that the optimized lifting-turnover mechanism meets seismic design requirements of nuclear power plants.