An improved particle swarm optimization(PSO)

called as dynamic target particle swarm optimization (DTPSO)

was proposed to use dynamic target strategy for solving complex multi-dimensional optimization problems by analyzing the position between individual particles

personal best and global best.As a specific example

the DTPSO was applied to the optimal design for hybrid rocket for a certain hybrid rocket motor of sub-orbital vehicle.The optimization results show that algorithm has strong search capability

and can also reach convergence rapidly and solve such problem effectively.All those can provide a theoretical reference for the research of sub-orbital vehicle engine's optimal design.