Abstract: The overall performance of nuclear power plant can be improved by decreasing self weight, which is one of the most important guidelines for the evaluation of design rationality of the nuclear power plant. Steam generator and pressurizer are important components in nuclear power plant. Therefore, the research focused on the method of minimizing the total weight of these two components. The design optimization of the total weight was carried out by self-developed codes based on complex algorithm. The results show that the optimized weight is 20.4% less than original, and it means that the optimization effect is obvious. The paper compares the difference of optimization results between coupled-devices and single component. The effects of operation parameters on the component weight were also analyzed in order to provide reference for engineering design.