Abstract: Weight is one of the criteria to evaluate nuclear power plant performance. Steam generator and pressurizer are important equipments in the primary loop. The plant can be improved through decreasing the weight of equipments if all requirements on the equipments are still fulfilled. Based on Qinshan nuclear power station parameters, the weight optimization codes for steam generator and pressurizer were developed. The particle swarm-simulated annealing method was used for multi-parameters weight optimization of two steam generators and one pressurizer in nuclear power plant. The results show that the total weight of the two equipments is reduced by 18.61%, and the optimization effect is obvious. The results can provide some insights for design of nuclear power plant.