Smart morphing aircraft has already been a hot point of the aeronautics and aerospace research, which is one of the most possible domains that should bring the revolutionary influences to the development of the aeronautics and aerospace technologies. At first the necessaries about the smart morphing aircraft are pointed in this paper:1) As the scopes of the altitude and the velocity of future aircrafts increase widely, the conventional rigid configuration may not satisfy the requirements of the aerodynamic and flight characteristics under different flight conditions; 2) For the multiple flight missions and tasks achieved by a single plane, it may be necessary for aircraft to alter the aerodynamic configuration in performing different missions; 3) In order to improve the overall aerodynamic performance of the existing aircraft, it is required to maintain excellent aerodynamic and flight performance through adjusting aerodynamic shape in all flight stages. This paper introduces the meanings of "morphing" and "smart" in the modern sense of smart morphing aircraft, in which "morphing" refers to the continuous deformation of different spatial scales (local, distributed, global) and time scales, covering a wide range. According to the deformation scale and function, it can be divided into three categories:local deformation (small deformation), distributed deformation (medium-scale deformation), and integral deformation (large-scale deformation). It can be divided into two types according to the way of realization:mechanical deformation and deformation based on smart material structure. It is also pointed out that the so-called "smart" in this field is basically confined to a single field such as smart materials or structures and intelligent control, which is far from ideal smart morphing. So this paper focuses on the basic scientific issues and key technologies involved in morphing technology. Secondly, from the first Wright Brothers powered aircraft controlled by flexible deformable wings in 1903 to the variable swept wing technology represented by F14 in the 1960s and 1970s, to the successful demonstration of continuous variable rear-edge curvature flight on Gulf Stream Ⅲ aircraft in recent years, the development process of the morphing aircraft is systematically introduced in this paper. Thirdly, the key problems and research progress of morphing aircraft are systematically introduced from the point of view of the key technology and the bottleneck of deformable aircraft design. From the design point of view, the main problems include requirement analysis and conceptual research of the smart morphing aircraft, design technology of overall and subsystem of smart morphing aircraft. From the perspective of basic science and bottleneck technology, the main problems lie in following aspects:aerodynamics, flight dynamics and flight control of morphing aircraft, morphing structure, drive and morphing control. Fourthly, the connotation of smart morphing aircraft, morphing technical indicators, morphing materials and structures, and cost-effectiveness analysis is discussed. Finally, the future development of smart morphing vehicle technologies is prospected, and it is pointed out that smart morphing aircraft technology is spiral development. On the one hand, we need to carry out extensive and systematic research on basic theory and key technology, starting from the foundation; on the other hand, we need to sort out the background requirements of one or several types of morphing aircraft from the engineering point of view, in order to tract the orderly and rapid development of this field.