Abstract: A large-scale low earth orbit satellite network reduces the demand for the capabilities of individual satellites by increasing the number of satellites, achieving global coverage, and providing users with reliable low-latency services with greater bandwidth, making it an important component of integrated space and terrestrial networks. The constant high-speed movement of satellites results in frequent changes in the network topology, coupled with limited payload and computing capabilities, posing certain routing challenges for large-scale low-orbit satellite networks. This paper addresses routing issues in satellite networks by simplifying the network structure. Based on network modularity technology, a network simplification algorithm is proposed that preserves the original characteristics of the network while significantly simplifying the network topology. The algorithm uses satellite node attributes and attributes of connections between satellites as evaluation criteria, while also considering the impact of link interruption probability to determine sets of satellite nodes that can be combined into modular nodes. In networks simplified using different algorithms, the same routing algorithm is used for routing queries to verify performance. Simulation results demonstrate that simplifying the network using the proposed algorithm preserves the original network characteristics while achieving rapid convergence and excellent results for routing algorithms in simplified networks.