The invention relates to a method and a manufacturing process (attached drawing) for producing an environmentally-friendly decorative board by using a fast-growing poplar rotary cut veneer, which mainly solve the problems of low bonding strength, high probability of cracking and warping, uncompacted corner, high formaldehyde release, low nail holding power, high probability of falling, poor water proofing, moisture proofing and fire proofing performance existing in the conventional decorative board. The production method and the manufacturing process are mainly characterized in that: the density of a finished board is determined by using the apparent density (actually measured) of the fast-growing poplar rotary cut veneer in comparison with the density of red pine; a compression ratio is determined according to the two densities; and the thickness of an assembly is determined by using the compression ratio. Modified urea-formaldehyde resin and melamine resin are mixed as an adhesive; and parameters for a hot pressing process of a board blank are determined according to the compression ratio, and curing temperature, time and pressure of an adhesive. Decorative paper which is soaked in the adhesive solution is adhered to the surface and the back surface of the board blank formed after hot pressing, and then secondary hot pressing is performed to finish the final environmentally-friendly decorative board. The production method and the manufacturing process have the advantages of mechanical property of the finished product beyond that of timber, no formaldehyde release, water proofing, moisture proofing, fire proofing and cracking prevention effects, high nail holding power, repeatedly detachable hardware and small variability.