The time slot planning of inter-satellite links directly determines the performance of the satellite network. Under the needs of inter-satellite ranging and communication, how to allocate inter-satellite links is the key to solving the problem. In the STDMA access mode, the division of inter-satellite network resources is not only the allocation of time slots, but also the allocation of satellite nodes. From the analysis of inter-satellite visibility, it can be known that each MEO satellite, excluding the currently invisible MEO satellites, plus the currently visible GEO/IGSO high-orbit satellites, the average total number is about 20.