The invention provides a multilayered composite material foam sandwich board and a preparation method. The multilayered composite material foam sandwich board is prepared from foam sandwiches, fibersand resin, wherein at least three layers of the foam sandwiches are arranged; each layer of the foam sandwich is formed by arraying unit modules; a resin filling groove is formed in an outer wall of each foam sandwich unit module; the fibers are distributed on the surfaces, except end parts, of each foam sandwich unit module; the resin is filled through the filling grooves and penetrates into thefibers; after the resin is cured, the foam sandwiches, the fibers and the resin form a whole body. According to the multilayered composite material foam sandwich board provided by the invention, the manufacturing cost is effectively reduced and the mechanical properties are improved; the preparation method of the multilayered composite material foam sandwich board, provided by the invention, adopts a groove type vacuum injection molding technology to distribute a flow channel on the surface of a core material and a mold is filled with the resin through the flow channel. The groove type vacuuminjection molding technology has the advantages that a high-penetration medium and a stripping material are not added, so that the preparation method is simple in technology and low in cost, and is especially suitable for preparing large-size, reinforced and sandwich abnormal-shaped structural parts.