Abstract: In order to obtain high-stiffness and good thermal stability of main supporting structure in space remote sensor, a flexible support structure was proposed to solve the contradiction of force and thermal constraints availably, which are two key environmental constraints on the imaging of the grating spectrometer. Firstly, according to the optical design requirements, the structure of the grating blank was determined. Secondly, the sensitivity of the sizes of the flexible support was analyzed by theoretical calculation,and their effects on bend rigidity were obtained. Optimum design was utilized to determine the final sizes. Finally, the surface figure precision and dynamic stiffness of the grating component in the thermal-structural coupling state were analyzed with finite element analysis(FEA) software. Simulation results demonstrate that design of the grating blank and its flexible support structure is reasonable, which can meet the requirements of the space application and supply the reference for further study and application.