The present invention provides a biomimetic composite material, a nacreous layer-mimetic material, a biomimetic nacre material and preparation methods thereof. The biomimetic composite material comprises multiple composite film formed from biomass fibers and an inorganic nanomaterial, wherein an organic polymer material is arranged between the multiple composite film layers or in the composite base body. The invention combines a high-mechanical-performance shellfish structure with a wood fiberboard to overcome the original defects of the fiberboard, improve the fiberboard performances and endow it with new special performances, so that the prepared material has dual functions of the fiberboard and the nanomaterial at the same time.