Abstract: The themal stress in a themal protection strIJcture(TPS)in the reentry spacecraft under the altemating in. orbit temperature condition during night is always an imponant issue. This paper investigates the bonded stmcture of“mid-density shield-silicon. metal"under ±100℃/5 cycles based on the typical themal condition of the low. eanh-orbit. Innuences of the bond-layer thickness on the themal stress and defomation are obtained by the finite elemem analysis(FEA)model based on ANsYs soware. nle optimal TPs bond-layer thickness is obtained for the application in the present themal condition according to the analysis of the FEA results, the themal stress theory and the bond processing. The FEA simulation results can be used for TPS themal-match property study and design.