Abstract: Coal blending combustion is a key strategy employed by thermal power plants to enhance coal quality and reduce power generation costs. The critical challenge lies in rapidly and effectively determining the optimal blending ratio under varying operating conditions to facilitate dynamic coal switching. This paper proposes a region model-based optimization method for the coal blending ratio. Firstly, the definition and basic concept of the feasible region for the coal blending ratio are introduced. Then, a construction method for the feasible region based on linear boundary functions and a vertex search algorithm is proposed. On this basis, a rapid calculation method for the optimal blending ratio based on the feasible region is established, along with a fast adjustment method for the blending ratio to accommodate sudden changes in operating conditions. Finally, case studies are conducted to verify the effectiveness of the proposed method.