Abstract: Satellites with high sensitive microwave payloads present a high demand for electromagnetic shielding efficiency of cabin panels. However, the usage of cables crossing cabin may significantly reduce the cabin electromagnetic shielding efficiency. In this article, a method for analyzing the electromagnetic shielding efficiency of the ideal cabin panels (without cables crossing the cabin) of spacecraft was proposed, and design principles of shielding the electromagnetic interference above 1 GHz were provided. Then, the mechanism by which the cables crossing cabin become the main factor affecting the efficiency of cabin panels shielding P-band (150 MHz to 1 GHz) electromagnetic wave was analyzed. A calculation formula for the interference current in relation with electromagnetic field strength was given. Finally, an electromagnetic compatibility (EMC) design method for the cables crossing cabin and cabin shielding was suggested, and a grounding resistance measurement method was offered to verify the grounding effectiveness of the cable shielding skin, which may contribute to identify the key control measures for the EMC implementation of the satellite assembly. The efficiency of the whole satellite EMC test has been effectively improved by the proposed method.