Biomass composite packaging board and preparation method thereof

The invention discloses a biomass composite packaging board which is prepared from the following raw materials in parts by weight: 40-50 parts of plant fibers, 5-45 parts of biomass ash, 0-30 parts of sludge, 5-13 parts of an adhesive, 35-70 parts of a dispersing agent and 100-240 parts of water, wherein the biomass ash is waste incineration fly ash and/or sludge incineration fly ash; the sludge is harmless sludge subjected to complete inactivation and complete sterilization; the length of the plant fibers is 0.5-4 mm; the preparation method comprises the following steps: (1) adding water into the plant fibers to prepare fiber slurry; (2) dissolving an adhesive with a dispersant, and then adding biomass ash or biomass ash and sludge to form a dispersion liquid; (3) uniformly mixing the fiber slurry and the dispersion liquid; (4) carrying out hot press molding on the mixed slurry in a mold, cooling and demolding; according to the board, the compressive strength and the bending strength of the board are enhance