This paper is aimed at investigate thermal and mechanical properties and internal mechanisms of stitched sandwich thermal protection structure applied in the hypersonic technology field. Based on representative volume element model, a finite element simulation analysis method was established to simulate the responses under combined thermal and mechanical loads. Internal temperature and stress distributions of the thermal protection structure were analyzed, as well as the evolutions with the loading history. The results show that the stitched sandwich thermal protection structure can effectively play the role of heat insulation when heating surface temperature was 1 073 K. Reducing effect of stitches as thermal channels on insulation performance is limited. however, thermal expansion mismatches of different components can result in stress concentration. Tensile stress state at the skin/core interfaces and possibly higher stress level inside core may cause damage and failure of the structure.