As an underactuated system,unpowered high speed aircraft should be considered control characteristics systematically in formation optimization.Based on the concept of"real-time reachable domain"and the analysis of the actual reachable region of high-speed aircraft,considering the number of cluster members and the fact that the actual cluster often contains multiple task groups,this paper proposes a dynamic grouping formation optimization method suitable for high-speed aircraft cluster.The simulation results show that the formation optimization method pro-posed in this paper can be used for integrated optimization of formation shape and parameters,flexibly adapt to a variety of flight tasks,and is also suitable for formation reconstruction with the number of cluster members changes,the method has important application value.