Abstract: As the sensitivity of primary satellite payloads continues to increase, progressively stringent requirements are imposed on limiting the electric field radiation emissions from star sensors. To meet these requirements, the circuit system and opto-mechanical structure shielding of star sensors were optimized to isolate them from satellite operating frequency bands. First, circuit design methods for suppressing electric field radiation emissions were proposed, targeting linear power supplies, interface filtering, electrical connectors, and cables. Then, considering the extravehicular installation characteristics of star sensors and the unenclosed nature of their optical systems, structural shielding schemes were proposed, including interface panel isolation, structural gap shielding, and optical channel partitions. Targeted structural shielding designs were implemented for key components such as printed circuit boards, detectors, and optical lenses. Finally, the effectiveness of the proposed suppression circuit designs and structural shielding designs was verified by the RE102 electric field radiation emission test specified in GJB 151B. This research can serve as a reference for the electromagnetic compatibility design of similar opto-electronic products.