Abstract: Objectives In view of the problem of insufficient autonomy and coordination of unmanned multi-agent collaborating on the surface environment, a digital twin-based multi-unmanned agent collaborative cruising strategy optimization method is proposed. Methods According to the construction of digital twin model of unmanned multi-agent physical entity, the mathematical model of unmanned multi-agent collaborative cruising is established to analyze the motion characteristics of the collaborative process of unmanned multi-agent. Aiming at the mutual influence and collaborative relationship of unmanned multi-agent, the unmanned multi-agent proximal strategy optimization algorithm is adopted to carry out the strategy optimization of unmanned multi-agent, and improve the cooperative cruising efficiency among unmanned multi-agent.Results The proposed method enhances the collaborative capability, decision-making efficiency, and robustness of multi-unmanned agents in complex maritime environments, as validated through the digital twin model of multi-agent systems built for the water surface scenario. Conclusions The study provides significant theoretical and practical support for the research on the optimization of cooperative cruising strategies of unmanned multi-agent on the water surface.