The invention provides a metal/composite material multilayer double-gradient energy-absorbing vibration-damping sandwich structure and a preparation method thereof. The metal/composite material multilayer double-gradient energy-absorbing vibration-damping sandwich structure comprises panels and a core layer arranged between the panels, the core layer consists of a unit cell structure, the unit cell structure is a thin-wall hollow tubular structure, and the wall thickness of the unit cell structure is in axial gradient change and/or the cell wall density is in radial gradient change. Core layerunit cell configuration gradients are integrated, the unit cell configuration gradients are realized by designing the unit cell height, the cell wall thickness, radial mixing of different materials and the like, and the multilayer sandwich structure with double gradients is formed in combination with structure gradients. The structure design and the preparation method provided by the invention are simple, the unit cell shape designability is strong, and an interlayer gap provides a space for embedding a multifunctional material. When the structure is subjected to vibration impact, the advantages of unit cell configuration gradients can be played, vibration propagation is isolated or attenuated through impedance mismatch, and more energy is absorbed through elastic-plastic deformation.