Abstract: The condenser is an important component in nuclear power plants,which dimension and weight will effect the economical performance and the arrangement of the nuclear power plants.In this paper,the calculation model is established according to the design experience.The corresponding codes are also developed,and the sensitivity of design parameters which influence the condenser weight is analyzed.The present design optimization of the condenser,taking the weight minimization as the objective,is carried out with the self-developed complex-genetic algorithm.The results show that the reference condenser design is far from the best scheme,and also verify the feasibility of the complex-genetic algorithm.