The invention discloses a high-strength micropore plastic-wood composite material panel and a preparation method thereof. The panel is prepared from benzylated fibrous wood powder, polyvinyl chloride plastic particles, p-toluenesulfonyl semicarbazide, N,N-dinitrosopentamethylene tetraamine, activated calcium carbonate powder, calcium stearate, lead sulfate tribasic, urea, salicylic acid, dibutyl phthalate and an antioxidant; the preparation method comprises the following steps: firstly preparing the fibrous wood powder from the wood powder by using a pulping method, preparing benzylated fibrous wood powder by modifying benzyl chloride, preparing the activated calcium carbonate by modifying calcium carbonate by using octadecanol polyoxyethylene ether sodium acetate, and then extruding a formed panel by using a step-by-step extrusion process. The panel disclosed by the invention is low in density, light in weight, large in rigidity, resistant in creep deformation, good in heat insulation and sound insulation, and convenient for transportation and mounting; the production manufacturing is convenient and environment-friendly, and the panel can be widely used for suspended ceilings, screens, wainscots, skirting lines, television background walls, door planks, racks and the like in the fields of building, traffic and decoration.