According to the operational characteristics of the high-speed network model of nearly polar constellation of micro-satellite, the definition of the high-speed network of constellation was given. The routing protocol adapted to the transmission model was analyzed, its deficiency under the model was illustrated and the calculation method of protocol overhead was deduced. Then the optimized protocol was provided. The high-speed network model of microsatellite constellation was established by using the NS3 network simulation platform, and the key performance indexes of the routing protocol were simulated before and after adopting the optimization strategy. The results show that the optimized routing algorithm reduces the overhead significantly, meanwhile it improves the throughput and packet arrival rate in the high-speed network. The performance of the high-speed network of nano-satellite constellation is optimized.