As an important component of future naval campaigns, the unmanned surface vehicle (USV) swarm is an important direction for the development of unmanned maritime assets in various counties. This paper first summarizes the current strategic planning and application status of USV swarms in foreign countries, then dissects the research progress of USV swarms in such aspects as cluster communication, battlefield situation awareness and cooperative task assignment. At the same time, the typical combat operation modes and main benefits of USV swarms are analyzed and assessed. Finally, current challenges that need to be tackled in USV swarm combat operation are analyzed, and countermeasures that can be taken against the technological development of USV swarm combat operation are predicted.