Space communication protocol is a challenging problem in the future of space network. Now Mobile IP routing is very popular in the wireless communication network. The research shows the Mobile IP network has the much similar features to the space network. A Space Communications Protocol Specification Network Protocol (SCPS-NP) routing algorithm based on Mobile IP routing is proposed in the paper. Firstly, some basic knowledge about SCPS is introduced. The flooding routing algorithm in SCPS-NP protocol is studied. A new routing algorithmoptimized Mobile IP routing algorithm based on QoS is proposed. In order to verify the effects of the algorithm, A simulation model using NS2 network simulation tools is built and the comparisons between traditional Mobile IP routing and improved SCPS-NP routing are provided. The results show that optimized routing algorithm based on QoS could achieve better performance than traditional Mobile IP. Further, a working prototype based on SCPS-NP Gateway is implemented to test the algorithm’s application. It shows that algorithm based on Mobile IP routing can be used in the future space network.