Autonomy evaluation is one of challenging research topics in unmanned systems, since the appropriate autonomy level can make the overall system more reliable and more robust.However, the autonomy level of human and unmanned vehicle is contextual about the changing situation and system states. This paper describes an approach to evaluate the autonomy for Unmanned Surface Vehicle (USV) system in the uncertain sea environment. Our research begins with the definition of teamwork-centered autonomy that the human and the unmanned vehicle are working in parallel and they are interdependent.Then, the method is proposed to resolve the evaluation problem about the system autonomy which is based on the group decision making with incomplete information. Finally, the simulation system included a system user agent, an USV agent and the sea environment agent with uncertainty, and demonstrated that this proposed method resolves the autonomy evaluation problem with feasibility and effectivity.Keywords-teamwork-centered autonomy; group decision making; adjustable autonomy; human-robot interaction; Un manned Surface Vehicle I.