Abstract An optimization procedure has been established aiming to design an integrated thermal protection system (ITPS) with minimum weight. The objective of this research is to establish the procedure and ensure its effectiveness. A corrugated sandwich panel has been chosen as the optimization problem. The ITPS geometric dimensions are considered as the design variables. The objective function is the mass per unit area of the ITPS and the constraint conditions are that the inner temperature and local stress both must be below certain values. The optimization problem is solved by developing a finite element simulation to represent the constraints. The parametric design language code in conjunction with the globally convergent method of moving asymptotes (GCMMA) has been developed for heat transfer analysis and thermal–mechanical analysis. The results show that the thicknesses of the top faceplate, bottom faceplate and insulation must be larger than 1 mm, 3.2 mm, and 134 mm, respectively, to guarantee that the constraint temperature is below the safe value. Thermal–mechanical sizing could save more than 37% of weight compared to the initial design. Different working conditions and failure modes of space vehicle should be analyzed in the future. The optimization procedure might be useful in future works.