By using the finite element thermal analysis method, the mode of the structure coupling analysis of the macro-micro motion platform is established, and the connecting frame and the thermal characteristic of the connecting frame and the flexible hinge platform is analyzed. It is found that the deformation amount of the connecting frame and the flexible hinge increases at the field load condition with temperature by analyzing the coupling field. During optimizing the key component size of the connecting frame in the motion platform during the sensitivity analysis, the maximum deformation amount of the connecting frame decreases by 20% after the size optimization and the total quality decreases by 22.7%, and the maximum stress decreases by 31.1%. The result from thermal structure coupling analysis and sensitivity optimization can make the motion platform more accurate and stable.