The hypersonic aircraft suffers more serious aerodynamic heating loads, the future aircraft thermal protection system should therefore satisfy more advanced requirements.Motivated by such trend, an optimal design method aiming at obtaining lightweight thermal protection structure for the aircraft was proposed in this study (Fig.1).A simplified one-dimensional heat transfer finite-element model considering the conditions of aerodynamic heating was developed (Fig.2), and the temperature distribution on various surfaces having different thickness was thus obtained.(Fig.3) The total weight of the lightweight thermal protection structure was optimized under the specified thermal-mechanical constraints.Based on the optimal sizes of the structure, the three-dimensional simulation for thermomechanical analysis was applied finally.The results of equivalent stress distribution shown that the optimization method is reasonable (Fig.4).