It is common to use passive isolator to protect the payload from the platform noise in space applications. The design of a passive isolator involves a trade-off between the resonant peak reduction and the high frequency attenuation. Firstly, the equation of motion and transfer function model for single-stage and two-stage connector model was derived, and then the multiobjective optimization model, in which the objective functions are the resonant peak reduction and the high frequency attenuation, was proposed,. Secondly, the multiobjective optimization design method for the design of the passive isolator was proposed, using the multiobjective evolutionary algorithm based on decomposition (MOEA/D). The simulation result shows that the proposed method is effective for the design process of the passive isolator, and can provide multiple candidate solutions for the designer.