A steady state genetic algorithm which can deal with several criterion functions was applied to the design optimization of Space Based Radar(SBR) satellite constellations. The discontinuous coverage model, inter-satellite links geometry model and bistatic moving target detection geometry model, which can describe the working properties of the SBR constellations, were developed. Then, the statistic evaluation and comprehensive evaluation indices were put forward, and the design optimization model was established. According to the particularities of this problem, steady state co-evolutionary genetic algorithm on the basis of searching in feasible solutions was used to deal with the design optimization problem. Finally, several design examples were presented, showing that the method is effective.