In this paper, the design optimization and simulation analysis on passive air-cooled finned heat sinks is carried-out for the heat dissipation issue of electronic components in the enclosed spaces of airborne. Firstly, a three-factor, four-level orthogonal experiment is designed based on the orthogonal experimental design method, which takes fin thickness, fin spacing and fin height into account. Then, CFD numerical simulation method is used to simulate and analyze heat sinks with different fin forms. Finally, the significance of the influence of various factors on the heat dissipation performance of the radiator is analyzed based on the extreme value analysis. The results show that the fin height has the greatest impact on the performance of the radiator, followed by the fin spacing and the fin thickness, and the optimal fin form is obtained.