This paper presents a bumper shield design for protection of a satellite structure system subjected to hypervelocity impact (above 6 km/s) from space debris. Especially, this study is focused on the optimization of the spaced plates (the so-called Whipple shield) design using the coupled SPH and Lagrangian FEM methods. This is because the SPH is a meshless method and it is efficient in hypervelocity impact analysis involving debris caused by fragmentation and penetration under hypervelocity impact. The Whipple shield is composed of multiple spaced plates where the first bumper plate is modeled as particles for SPH simulation while the rear wall is modeled as elements for FEM. The appropriate smoothing length and mesh size were determined taking into account computational cost and accuracy and the erosion scheme is adopted to avoid numerical error due to large deformation. After verification for the comparison with previous experimental works, the optimal plate structure is proposed considering multi design objectives based on parameter optimization.