Abstract: To address the severe challenges posed by the rapid technological iteration of modern anti-ship missiles to the terminal soft-kill defense of naval vessels, the operational requirements for shipborne off-board decoy countermeasures are clarified and the advanced foreign development experience is systematically summarized. A systematic review and comparative analysis are adopted, with a focus on investigating typical shipborne off-board decoy equipment and their supporting ammunition systems from the United States, Germany, and France. The technological evolution and performance characteristics are thoroughly analyzed from the perspectives of launch systems, ammunition types, and operational employment. Five core operational modes of off-board decoy countermeasures are identified, namely false target interference, dynamic deflection interference, suppression interference, attenuation interference, and combined interference. In addition, the core technological features of foreign technical systems are extracted across three dimensions: launch systems, ammunition technology, and operational application. Significant advanced experiences are accumulated by foreign countries in four major directions: operational system construction, universalization of launch devices, intelligent ammunition development, and adaptation to diversified platforms.