A structured frame for the design optimization problem of satellite platform structure was established through the definition, flow and modification research of design parameters in the ANSYS/CATIA system. Problems with creating complex satellite structure FEA (Finite Element Analysis) models were discussed, including the idealization of real structure, as well as embedment of APDL (ANSYS Parametric Design Language) programme developed specially for the pre-processing and post-processing of FEA model. The optimization model was established under structural design requirements, and a graded optimization method was applied for calculation. Light-weight design schemes for two satellite platform structure were obtained through the subsequently optimization implemented using approaches put forward previously. The optimization design problems of two satellite platform structure were settled well, and work done in this paper provides certain reference value for optimization of other spacecraft structures.