Abstract: In the systematic operation, ship formation navigation is faced with the challenges of equipment damage, electromagnetic interference and other complex operational environments. To solve this problem, this paper proposes a distributed network-based cooperative navigation system and method for surface warship formation to improve the robustness and flexibility of ship navigation in complex environment. The formation cooperative navigation system is divided into equipment level, subsystem level and system level. At the equipment level, the original navigation data of GNSS / INS is output. At the subsystem level, the node navigation data is output. At the system level, the formation cooperative navigation data is generated by fusion. In order to realize the data fusion of formation cooperative navigation at system level, a distributed formation cooperative navigation network is constructed by Floyd algorithm based on the principle of shortest baseline transmission path, and the node cooperative navigation data is generated through dynamic baseline transfer on the basis of the node navigation data. Then, the formation cooperative navigation data is output by fusing the cooperative navigation data of multiple nodes through weighted least squares. The simulation results show that the method has successfully constructed a distributed cooperative navigation network, which ensures the uninterrupted navigation of the damaged nodes through navigation support, and improves the navigation accuracy of the disturbed nodes through precision support. Distributed cooperative navigation has the advantages of anti-damage, anti-jamming and improving accuracy, and can effectively deal with complex combat environments.