Maritime unmanned system are crucial for future intelligent and unmanned warfare. They have become a new height of competition in the maritime domain and will play an increasingly important role in national defense security. Considering the development demand for national intelligence and unmanned strategies, the study analyzes the development status of maritime unmanned systems and corresponding technologies in China and abroad from the aspects of strategic planning and conceptual guidance, technological research and equipment development, and system demonstration and capability verification. The challenges and trends for the development of maritime unmanned systems are summarized and key technical challenges are proposed. Moreover, development pathways of maritime unmanned systems in key directions are explored and countermeasures to promote the sustained, steady, and rapid development of maritime unmanned systems are recommended from the perspectives of overall thinking, system composition, equipment development, and technology breakthroughs.