The invention discloses high-heat-release Al/CuO 3D nuclear shell array structured thermite with higher load. A preparation method of the thermite comprises the following steps: prepared foam copper pieces are put in chemical cleaning liquid for cleaning to obtain brassy foam copper without an organic matter layer and an oxide layer; and then, the obtained foam copper is quickly put in potassium hydroxide solution with a certain concentration for anodic oxidation to obtain a copper hydroxide array. After flushing and drying, a copper oxide three-dimensional array structure is obtained throughtemperature programming in a tube furnace; and finally, Al is deposited on the surface of a copper oxide three-dimensional array through a magnetron sputtering deposition mode to form the Al/CuO nanometer 3D nuclear shell array structured thermite. Compared with common Al/CuO thermite, the thermite has the advantages of uniform compounding of oxidants/fuels, higher array load density, no crack, high adhesive force and excellent heat release performance.