The unmanned boat is the key unmanned equipment developed in recent years. The unmanned boat has the characteristics of small size and flexible movement and it can perform military tasks such as patrol, reconnaissance, and attack on ships. Because of its operational characteristics, radar wave stealth application is also more common. The surface design of an unmanned boat is simple, but the surface equipment on the boat is not focused on, and there is much messy surface equipment, which is the focus of radar wave stealth design. In this paper, the radar stealth threat, stealth key technology, and stealth applicability faced by unmanned boats with high radar stealth are discussed, which provides a reference for the research on radar stealth requirements, stealth performance realization, and stealth combat of unmanned boats.