Morphing aircraft, overcoming the limitations of traditional fixed configurations, represents a critical direction in aircraft development. Their core principle lies in adjusting the airframe configuration to achieve optimal aerodynamic profiles for diverse operational environments, thereby significantly enhancing flight performance. After years of development, morphing aircraft exhibits the following characteristics: (1) Evolution from rigid deformation to flexible continuous deformation; (2) Progression from low-speed to high-speed applications; (3) Transition from single-medium to cross-medium flight; (4) Expansion of operational domains from singular airspace to integrated airspace domains. Deformable structures constitute a key enabling technology for morphing aircraft, primarily encompassing skins, supporting structures, and actuation systems. Skin technology has evolved from rigid to flexible skins. Moving beyond the initially employed metal skins, contemporary developments include composite material skins, smart skins based on shape memory polymers and piezoelectric responsive materials, multi-medium adaptive reconfigurable skins, and thermal protectiondeformable integrated skins. This flexible skin system not only grants adaptive surface deformation capabilities but also maintains the continuity of the airframe surface. Structural design is shifting from hinge-based mechanisms towards continuous deformation structures. Hinge-based wing morphing systems enable large-angle adjustments of aerodynamic surfaces. In contrast, continuous deformation structures not only possess substantial deformation capacity but also achieve precise aerodynamic profile matching while preserving airframe continuity. This capability, coupled with space deployment mechanisms, enables multi-medium transition capabilities, such as switching between underwater navigation and aerial flight. Actuation systems for morphing aircraft are transitioning from traditional motor-hydraulic actuators towards smart actuation, realized through the integration of active deformation units like dielectric elastomers, piezoelectric stack actuators, and shape memory alloys. This paper reviews the morphing configurations and research progress on deformable structures, focusing on their applications in unmanned aerial vehicles (UAVs), cross-medium vehicles, civil airliners, and aerospace vehicles. Building on this foundation, it outlines future development directions and primary challenges, aiming to provide a reference for innovative research in morphing aircraft technology.