The 6-DOF parallel platform in this paper is a kind of Stewart platform. It can be used as supporting structure for telescope secondary mirror. In order to adapt the special dynamic environment of the telescope secondary mirror and to be installed in extremely narrow space, a unique parallel platform is designed. PSS Stewart platform and SPS Stewart platform are analyzed and compared. Then the PSS Stewart platform is chosen for detailed design. The virtual prototyping model of the parallel platform is built. The model is used for the analysis and calculation of multi-body dynamics. With the help of ANSYS, the finite element model of the platform is built and then the analysis is performed. According to the above analysis the experimental prototype of the platform is built.