Abstract: A new type vector nozzle is proposed to improve the maneuverability and stability of amphibious vehicle. The nozzle which has two degrees of freedom in pitch and rotation can change the direction of the water jet and output a three-dimensional vector thrust. According to the waterjet propulsion theory of amphibious vehicle，the basic parameters of pump which can satisfy the power demand and the platform restriction are calculated. The structure and control strategy of vector nozzle integrated with the pump are designed according to the calculated diameter. The output vector thrusts at different vehicle speeds，pump rotation speeds，pitch and rotation angles are calculated using the computation fluid dynamics simulation software Fluent. The maneuvering mechanisms of non-vector waterjet propulsion amphibious vehicle，single vector waterjet propulsion amphibious vehicle and dual vector waterjet propulsion amphibious vehicle are analyzed and compared. The influence of vector waterjet on the seakeeping performance of amphibious vehicle is analyzed. The seakeeping dynamics equation and the pitch-roll moment equation are established. On this basis，the pitch-roll stability control strategy of vector propulsion amphibious vehicle is proposed. The simulated results show that the axial thrust decreases with the increase in pitch angle，the pitch thrust or the yaw thrust increases with the increasing pitch angle. The comparison results demonstrate that, compared with non-vector waterjet propulsion amphibious vehicle，the vector waterjet propulsion amphibious vehicle has obvious advantages in lateral translation，oblique translation，in-situ steering and propulison efficiency. The vector waterjet designed produces the vector thrust which can not only provide longitudinal driving force for the amphibious vehicle，but also lateral force，yaw and pitch torque，providing a new scheme for improving the maneuverability and stability of the future amphibious unmanned platform.

Key words: amphibiousvehicle, waterjetpropulsion, vectornozzle, maneuverability, seakeeping, computationfluiddynamicssimulation