Abstract: Flexible wing design for morphing aircraft poses a key technical challenge in achieving adaptive deformation to improve aerodynamic efficiency and mission adaptability. To meet the requirements of large deformation capacity, low actuation energy consumption, high load-bearing stiffness, and multiple deformation modes for morphing aircraft flexible wings, this paper establishes a novel design method for flexible wing support structures based on U-type honeycombs. A large-deformation theoretical model considering geometric nonlinearity was developed to systematically analyze the influence of U-type honeycomb geometric parameters on deformation capacity. Analysis shows that the adopted U-type honeycomb structure achieves a global deformation amplification effect exceeding 24.87 times the local material strain, demonstrating excellent large-deformation capability. Based on this, an innovative flexible wing structural scheme was designed and validated through numerical simulations and 3D-printed prototype experiments. Results indicate that the in-plane deformation of the flexible wing achieves 32% spanwise elongation, 29° backward sweep angle variation, and 30° forward sweep angle variation. Spanwise stretching and sweep angle variation tests further confirm coordinated deformation while meeting design specifications. The proposed solution integrates multiple deformation modes within a single structure, providing theoretical reference and an engineering-feasible approach for morphing aircraft flexible wing skeleton design.