The invention provides a preparation method of a four-layer composite board for a brazed cellular structure, and belongs to the field of manufacturing method of surface composite boards for brazed cellular structures. By adoption of the preparation method of the four-layer composite board for the brazed cellular structure, the technical problem that an existing surface board core alloy for a brazed cellular structure is poor in strength after being brazed at a high temperature is solved. The preparation method comprises the steps that firstly, an Al-1.0Si-0.6Cu-0.75Mg-0.35Mn alloy ingot is pretreated; secondly, a hot-rolled slab is prepared; and thirdly, cold rolling, annealing, flattening and shearing are conducted. The surface board, prepared through the method, for the brazed cellular structure meets the designed material selection requirement of brazed cellular-structure boards and can better facilitate application and popularization of the brazed cellular-structure boards. The four-layer composite board prepared through the method is applied to the surfaces of the brazed cellular structural boards.