In this paper, the fluid solid coupling method is used and the FE (Finite Element) analysis is conducted for the PSSS (Periodic Symmetric Struts Support) of the large scale GT(Gas Turbine), and the overall thermal stress and thermal deformation are obtained. From the structure feature of the gas turbine, the initial boundary conditions of the high-temperature gas flow field and thermal deformation are analyzed at first. Then the coupling relationship between fluid and solid two phases is expressed mathematically, and the thermal conductivity is considered for calculation of heat transfer process, and the overall temperature field is obtained. Finally the thermal boundary condition of PSSS is defined and the structural FE analysis is conducted. At the same time, the thermal stress field and thermal deformation field are discussed for overall PSSS structure.