Complex algorithm is one of the most commonly used methods in the mechanical design optimization,such as the optimization of nuclear component.An improved method,complex-genetic algorithm(CGA),is developed based on traditional complex algorithm(TCA),in which the disadvantages of TCA have been overcome.An optimal calculation,which represents the pressurizer,is carried out in order to analyze the optimization capability of CGA.The results show that CGA has better optimizing performance than TCA.