To get more appropriate louvered fin structure of a series of subcompact radiators, Fluent was used to analyze the subcompact radiator louvered fins numerically. The fin model was verified availably by testing the error between the simulation results and experimental ones. Through modifying the critical dimension of louvered fin models, the friction factor f and the heat factor j of subcompact radiator louvered fins under different fin height were obtained. The regression analysis indicated that the friction factor was linear with fin height, and the heat factor was the power function of fin height. The dimensionless parameter j/f1/3was introduced to evaluate the comprehensive performance of fins, and the research indicated that the performance would be best when the fin height was 8.94mm. The result has a certain practical value for improving the performance of subcompact radiators.