The inter-satellite link system includes a data plane and a management plane. The data plane uses a layered structure to provide basic inter-satellite ranging, time synchronization, and packet data transmission services, and supports future extended application services. The network protocol of the layered structure of the navigation constellation inter-satellite link refers to the ISO/OSI reference model, and has been simplified according to the network characteristics of the navigation constellation. The network protocol stack is divided into five parts: physical layer, link layer, network layer, transport layer, and application layer.