Abstract: Silicone rubber core mold is one of the key tooling to realize the co-curing molding process of resin matrix thermosetting composite hat-stiffened structures, while in the curing and heating process of prepreg, the heat inflation of silicone rubber core mold needs to be eliminated by prefabricating appropriate adjusting hole, so as to ensure the forming quality of hat-stiffened structure. The silicone rubber core molds with different structures were simulated using computer by establishing the thermo-mechanical coupled finite element analysis model for the prefabricated adjusting hole of silicone rubber core mold, thus the optimal size range of the prefabricated adjusting hole of silicone rubber mold which can realize the collaborative manufacture of shape and properties of composite hat-stiffened structures' was obtained firstly. Then, the possible impact factors of heating expansion of silicone rubber core mold were analyzed comprehensively, so that the calculation model of prefabricated adjusting hole considering the volume correction coefficient was found. After that, the volume correction coefficient for the prefabricated adjusting hole of core mold was regressed by finite element method, and the regressed correction coefficient was employed to conduct the simulation verification of the hat-stiffened structures with different sizes of cross-sections. Thus, the relative accurate theoretical calculating model for prefabricated adjusting hole was determined. Finally, the correctness of the mathematical model and the finite element analysis was verified by experiments, which would provide theory and experimental basis for the fabrication of composite hat-stiffened structures.