Abstract: To more accurately predict the flow resistance of the low temperature economizer in complex flow field in engineering designs, this paper proposes a method to simulate the resistance characteristics by using the resistance coefficient of the low temperature economizer obtained by direct simulation of the parts of the fin tube bundles and the porous media model.Based on this method, the resistance characteristics of a low temperature economizer installed in a coal-fired power station is studied. It is found that the bent narrow exit_and_entrance flue type will affect the total pressure distribution of the low temperature economizer, but it has relatively samller effects on the resistance of the low temperature economizer. The fin tube structure and the macro structure of the low temperature economizer are the main reasons for the formation of its high resistance. The error between the predicted value and the measured value of the resistance is small, which indicates that the numerical simulation method proposed in this study is able to meet the needs of engineering design.