The invention discloses a novel decorative board with a foam heat-insulation wood plastic layer, and belongs to the technical field of forming technologies of heat-insulation decorative boards. A preparation method comprises the five steps that 1, materials are mixed; 2, the mixed materials are put into an extruder to be extruded; 3, sizing is conducted; 4, bonding is conducted; and 5, cutting andpackaging are conducted. The technological conditions are mild, continuous production can be achieved, a waterproof and moisture-proof layer is made of cheap PP and PE to serve as a bottom layer, thus the cost is lowered, and through the enhancement effect of wood fibers, the board is not prone to cracking. The gluing performance of the flame-retardant decorative board prepared through the methodmeets the national standard requirements, and a substrate is endowed with flame-retardant performance; the mechanical properties of the substrate are not affected, the formaldehyde release amount isalso above the E1 level, and thus safety and environmental protection are achieved; and meanwhile, the natural texture of wood is maintained, and the decorative effect is good.