As intelligent technologies and unmanned systems develop rapidly, the concept of cross-domain cooperative technology of intelligent unmanned swarm systems has emerged, received widespread attention, and gradually become the high ground in the competition of unmanned system technologies among countries worldwide. Based on the development demand for the cross-domain cooperative technology of intelligent unmanned swarm systems in China, this study summarizes the research status of the cross-domain cooperative technology in typical unmanned scenarios such as sea–air, air–ground, and sea–ground/sea–ground–air, and thoroughly analyzes the current status, technological demand, and key research directions of the technology. Additionally, countermeasures and suggestions are proposed to promote the steady and rapid development of the cross-domain cooperative technology from the perspectives of overall concept, system architecture, theoretical innovation, and technological breakthroughs, with the aim of facilitating the sustained development of unmanned systems in China.