Abstract: Wingtip morphing unmanned aerial vehicle (UAV) can change the wingtip cant angle according to different flight state requirements. When designing the connection stiffness of the wingtip and the main wing (referred to as the wingtip connection structure stiffness), it is necessary to comprehensively consider the influence of different wingtip cant angles on the flutter characteristics of the wingtip morphing UAV. In this paper, a quasi-static modeling method is adopted to establish the full aircraft dynamic finite element model of the wingtip morphing UAV under different wingtip connection structure stiffness and wingtip cant angles. The dimensionless wingtip connection structure stiffness is introduced to study the influence law of the wingtip connection structure stiffness on the flutter characteristics of the wingtip morphing UAV, providing a reference for the design of the wingtip connection structure stiffness. The analysis results show that when the wingtip cant angle of the wingtip morphing UAV is within 30°, the change of the wingtip connection structure stiffness has a small impact on the flutter speed of the wingtip morphing UAV; when the wingtip cant angle is greater than 30°, the change of the wingtip connection structure stiffness has a significant impact on the flutter characteristics of the UAV, and a complex change situation such as the increase and decrease of the flutter speed and multi-step sudden changes occurs. When selecting the wingtip connection structure stiffness, with the increase of the wingtip cant angle, the flutter speed of the wingtip morphing UAV shows an overall trend of first increasing and then decreasing; when the wingtip cant angle reaches a certain value, the flutter speed decreases, the flutter frequency increases, and the flutter form changes from body freedom flutter to bending-torsion coupling flutter.