Abstract: It is necessary for large scale sCO₂ boilers to adopt module design to deal with the pressure drop penalty effect. Due to the higher sCO₂ inlet temperatures and lower in-tube convective heat transfer coefficients compared to water boilers, the cooling wall modules in sCO₂ boilers have a high risk of being overheated. Therefore, ensuring safety of cooling wall is a key issue for sCO₂ boiler design. In a sCO₂ boiler, the heat flux of flue gas side and thermal parameters and module geometric dimensions of sCO₂ side have different distribution characteristics. Thus, matching the flue gas side and the sCO₂ side can achieve different wall temperature distributions. Optimizing the matching relationships can effectively reduce the cooling wall temperatures. Focused on large scale sCO₂ boilers, this paper studied a double-reheat boiler applied to a 1000MW power plant. A numerical model coupling thermodynamic cycle with flow and heat transfer in boiler modules was established, and the cooling wall temperature distributions under different layout schemes were compared. The matching strategy of flue gas side and sCO₂ side to reduce the cooling wall temperatures was proposed. It is shown that, the "6-Module Layout" which follows the principle of matching low-temperature fluid with high heat flux over entire temperature range of flue gas decreases the cooling wall temperatures effectively. The cooling wall temperatures are further reduced by arranging the cooling wall modules based on the principle of matching high allowable-heat-flux with high heat flux in furnace. The matching strategy proposed here decreases the cooling wall temperatures effectively, providing a reference for sCO₂ boiler design.