Improving shielding effectiveness of the shield cavity can enhance the protection capability of High Intensity Radiated Field (HIRF) of the airborne electronic system in civil aviation.Based on Robinsons model,a modified model is proposed to calculate the shielding effectiveness of a metallic shield cavity with non-central aperture array.The airborne communication equipment in civil aviation is taken as the research object.The modified model is utilized to compute the shielding effectiveness of the airborne communication equipment in civil aviation,and the correctness of the model is verified by comparing with the results of the 3D electromagnetic simulation software.Moreover,the impact of different aperture arrays,frequencies and positions on the internal electric field distribution of the equipment is analyzed by software simulation.The simulation result can serve as a reference for the design of a shield cavity and the layout of internal sensitive devices for airborne electronic equipment in civil aviation.