The invention discloses a method for producing a wood plastic wallboard. The method comprises the following steps: drying calcium sulfate to remove water, mixing calcium sulfate, an aluminate couplingagent, stearic acid and oxidized polyethlene wax in a high/low-speed mixing machine, crushing the plant fiber, grinding the plant fiber to obtain plant fiber powder, drying the plant fiber powder, during the process, and adding a modifier and oxidized polyethlene wax to obtain modified plant fiber; uniformly stirring waste plastic, modified plant fiber, a modified functional material and other auxiliary agents at the temperature of 60 DEG C, 85 DEG C, 100 DEG C and 125 DEG C in order and mixing the materials to obtain a mixture, and processing the mixture to obtain the wallboard. The functional material is synthesized, during the process, a coupling agent, stearic acid and oxidized polyethlene wax can be fusion, the materials are fully attached on the surface of calcium sulfate for modification, the material, the plastic, wood powder and other chemical raw materials are subjected to a full chemical reaction while mixing, and the impact strength resistance and shore hardness can be increased for the product.