The invention relates to the field of ecological wood and provides ecological wood and a preparation method thereof. The ecological wood has the advantages of good waterproof and moisture-proof effects, no harmful substances such as formaldehyde, methylbenzene and the like, good flame-retardant effect, small smoke production volume, good ductility, toughness and impact resistance, recyclability, acid/alkali corrosion resistance and long service life. The ecological wood comprises the following ingredients in parts by weight: 60-70 parts of chloride-vinegar copolymer resin, 9-11 parts of impact modifier, 20-30 parts of plant fiber, 1-3 parts of coupling agent, 10-20 parts of smoke inhibitor, 5-15 parts of activated clay, 0.5-1.5 parts of lubricant, 4-6 parts of activator, 8-10 parts of environment-friendly flame retardant, 4-8 parts of heat stabilizer, 0.5-1.5 parts of odorless crosslinker, 1-5 parts of foaming agent and 1-5 parts of deammoniation agent. The ecological wood is prepared in a manner that all the ingredients are subjected to pretreatment by the plant fiber, mixing by a closed mixer, cooking by an open mixer, tabletting by a tabletting machine and closed-pore foaming in a mold, cooling and mold stabilizing.