The invention discloses an interface metallurgical bonding aluminum foam slab and a preparation method thereof. The slab is prepared by forming a uniform and integrated skin layer on a foamed aluminum core layer through an interface metallurgical method; the skin layer is a dense aluminum plate which is formed by a foamed aluminum core layer substrate undergone fusion, and the thickness of the skin layer is 0.5mm to 2mm. The preparation method comprises the steps of putting the pretreated foamed aluminum core layer substrate on an interface heating platform of an interface heating furnace, meanwhile, applying uniformly static pressure on a stop block through a pressing machine, forming the skin layer which is integrated with the core layer on the surface of a foamed aluminum core layer slab. The preparation of a foam aluminum sandwich panel of which the integrated structure is composed of the skin layer and the core layer is realized, the stability of performance of the foam aluminum sandwich panel is improved. The problem that the original foam aluminum sandwich panel is not stable is solved, and excellent properties of a foam aluminum sandwich structure is maintained.