To develop the design,ing method of airport flood preventlOn engmeermg , this paper mtroduce a new design method ,risk-return analysis method. The method select the design plan by analyzing the economlC return , soclety return and military return synthetically. And the paper made discusslOns on defining and computmg of each return. By usmg the risk-return analysis method , we selected the best design plan of a alrport flood defending constructure engmeenng.