The construction of space-based information service system integrating positioning, navigation, timing, remote sensing and communication (PNTRC) will provide a powerful guarantee for cross-border real-time communication, global tracking of moving targets, and rapid response to disasters. It also puts forward new requirements for efficient network communications, especially satellite routing planning algorithms. In order to optimize the communication link and reduce the time delay, this paper makes full use of the advantages of direct view between spatial grids and high coding calculation efficiency, and proposes a satellite grid space grid computing method. This paper introduces the GeoSOT-3D grid subdivision model and applies it to the aerospace, proposes an aerospace grid index big table, and develops a set of satellite visibility analysis and inter-satellite routing planning by querying the grid visibility look-up table. In order to verify the feasibility and applicability of the proposed algorithm, based on the coding generation principle and visualization of the aerospace grid coordinate test platform, a global grid index big table is established. Three sets of verification work are carried out after simulating the 90/15/2 Walker constellation, including grid big table experiment, inter-satellite calculation efficiency experiment, and inter-satellite route planning experiment. The experiments verify the feasibility of the inter-satellite link calculation and application process in terms of organization, storage, calculation and planning. The efficiency of grid visibility analysis to determine whether the satellite connection grid code is negative is 2.2 times higher than the traditional algorithm, and the efficiency of the visibility analysis based on the pre-established universal visibility table is 20.9 times higher than the traditional algorithm. The efficiency of grid-based inter-satellite routing planning is improved by nearly 25 times under the shortest distance constraint, and approximately 20 times under the minimum hop count constraint. Through theoretical analysis and experimental verification, it is initially shown that the algorithm is feasible and efficient. We hope that the proposed algorithm can be used in emergency communications, disaster warning, maritime rescue, etc., and also contribute to the construction of satellite Internet.