Spare parts are the material basis for equipment maintenance in nuclear power plants. However, holding excessive spare parts inventory will increase the operating cost of nuclear power plants. By setting reasonable spare parts inventory parameters, a reasonable balance between supply guarantee and inventory control can be found. To solve the problem of spare parts inventory parameter setting, genetic algorithm was introduced into the field of spare parts inventory parameter optimization. By establishing the evaluation method to evaluate the quality of spare parts inventory parameters, the setting of spare parts inventory parameters was transformed into a multivariable optimization problem, and the genetic algorithm was used to calculate the optimal inventory parameters. The spare parts of nuclear power plants were selected for simulation testing. When the spare parts are added with multiple consumption fluctuations, the spare parts inventory parameters calculated by genetic algorithm are better than those in the current database. The results show that genetic algorithm has important practical value in the field of spare parts inventory parameter optimization.