The present paper focuses on the multiple-object optimizing design of heat exchangers. An optimizing model of plate-fin heat exchanhers has been established for multiple-object functions to take account of the variation of the heat transfer coefficients and friction factors with flow length and the effect of flow nonuniformity on the heat exchanger performance, Two optimizing design program packages have been edited and the capability has been successfully demonstracted by the design of a heat exchanger used in aircraft.