The development of space-based information systems has gone through three stages: single-satellite application mode, constellation application mode, and networked application mode. At present, the next development goals of the major space-faring nations in the world are all positioned on the basis of continuing to improve the types of satellite systems and enhance the functions of satellite systems, vigorously develop and establish a new type of comprehensive space system that is networked, and integrate different orbits, different types, and different performance satellites or constellation systems, as well as ground support systems, according to the principle of maximizing the effective comprehensive use of information resources, through the integrated system of satellite-to-earth and inter-satellite links, to provide seamless real-time access services for fixed or mobile users, thereby improving the system benefits of space-based information systems. Inter-satellite link technology, as the bridge connecting different satellite nodes, is the key to the evolution of space-based information systems.