The invention discloses an epoxy resin based composite material plate with acoustic impedance characteristics and a preparation method of the epoxy resin based composite material plate and belongs tothe technical field of composite materials and functional materials. The epoxy resin based composite material plate is prepared from epoxy resins, chloroprene rubber vulcanized rubber powder, aluminum-iron alloy granules, lead powder, acetone, phthalic anhydride, glass fiber cloth and diethylenetriamine. With the adoption of the mixture of organic chloroprene rubber vulcanized rubber powder, inorganic aluminum-iron alloy granules and lead powder and with the adoption of a method for respectively coating the inner and outer layers, the inner and outer layers are mutually overlapped, so that theprepared composite material has excellent acoustic impedance characteristic and strength characteristic, the acoustic impedance graded distribution of the composite material is stable and uniform, and the operating repeatability is high; and by regulating the relative usage amount of the packing, the composite material can achieve an acoustic impedance value in a certain range. Compared with materials made from tungsten powder and the like in the market, the composite material disclosed by the invention has low cost.