This work studies the influence of characteristic parameters on the heat transfer and stress distribution for the thermal barrier caotings used in a novel 700℃ dual-pipe system. The finite element sequential coupling method was used and revealed that the thickness ratio of the ceramic layers, thermal conductivity of the outer ceramic layer, thermal expansion coefficient, cooling steam temperature, and pressure simutaneously have significant effects on the temperature and stress distribution of the coated steam dual-pipe system. On this basis, a structural optimization method for the multilayer heterogeneous coating system was developed by using MATLAB and ABAQUS platforms. And the optimal geometric sizes and material properties were identified. Furthermore, it was discovered that the inner surface temperature of P91 steel pipes can be decreased by about 27℃ and the maximum Mises stress at the interface between thermal growth oxide and bond coat can be decreased by about 151MPa, respectively. The results show that the proposed systematic optimization method can be used to automatically determine the optimal key characteristic parameters of multilayer heterogeneous coating systems, resulting in improved thermal management and reduced stress on critical components. These findings have important implications for the design and optimization of thermal barrier coatings in high-temperature applications.