Abstract: A heat transfer model on a fin tube radiator under micro gravity is established in this paper.The maximum heat discharge per unit mass and the minimum power to drive fluid are adopted as the optimum objects,and the fin tube radiator of aircraft is thus optimally analyzed.The DSFD method is applied to solve a non linear optimum problem with multi objects and multi constraints and the method to optimize the fin tube radiator on the whole is postulated.The optimum designing parameters for the fin tube radiator is provided as a result.