Abstract: A mathematical model was established to calculate the pressurizer volume and weight of nuclear power plants, and the corresponding computer code was programmed. The effects of primary circuit working pressure and reactor coolant outlet temperature on the pressurizer volume and weight were also analyzed. Suitable optimization variables and constraints were chosen, and then the optimal design of the pressurizer weight was carried out based on the hybrid genetic algorithm. The results show that the pressurizer weight optimized with this scheme is 15.3% less than that of the original, and the optimization effect is obvious.