Space frame structures have the different shapes according to generation principle and member connection method. Thus, space frame dome structures need the optimal shape design method according to requirements. The optimal design method for space frame structures generally adopts the size and shape optimization method that aims at optimal weight. This optimization method shows the results which consider the minimum weight with appropriate shapes from stress and displacement constraints. But, it is not easy to secure the maximum stiffness of structure because the optimal weight design is established by the given constraint conditions. Therefore, this study finds out the optimal structural shape that has the maximum stiffness through the stiffness optimization method. To this end, we first select the various types of space frame dome structures and generate the dome structure shapes using VBA(Visual Basic for Application). Also, we consider the various load conditions and perform the optimal stiffness design for the performance comparison of dome structures. In this way, the total weights and displacements are evaluated during the stiffness optimization process according to the height variations of dome structures.