In this study,CFD method is used to analyze the performance of an automobile tube type shutter radiator. The local iterative method based on the local model iterative calculation is used to calculate the heat transfer performance of the integral radiator. At the same time,the resistance characteristics of the radiator are simulated by using porous media instead of the dispersion zone. The results show that the simulated heat dissipation of the whole loose zone can be estimated by using the results of several local models. It is feasible to estimate the heat dissipating capacity of the radiator by averaging the total mass flow rate of the radiator as the mass flow rate at each flat tube inlet. The results of the local iteration method and the porous medium model simulation agree well with the experimental results,and provide a new idea for the performance analysis of the integral radiator.