The invention discloses a high-toughness flame-retardant foamed PVC wood-plastic board. The high-toughness flame-retardant foamed PVC wood-plastic board comprises PVC resin, fiber powder, nanometer light calcium carbonate, rutile titanium dioxide, methyltin mercaptide, antimony trioxide, polyacrylonitrile-based carbon fibers, a PVC flexibilizer, a coupling agent, liquid triphenyl phosphite, a PVC modification aid, chlorinated paraffin, silicone oil and an AC foaming agent. The invention also discloses a preparation method for the PVC wood-plastic board. The preparation method for PVC wood-plastic board in the invention is simple in process and easy to operate; and the prepared PVC wood-plastic board has a plurality of advantages like good thermal stability, good ageing resistance, good anti-oxidizability, good impact resistance, good wear resistance, good insulating properties and good flame resistance.