The present invention belongs to a special cone-shaped double-screw extruding machine for a wood-plastic composite material of the plastic processing machine, including a power source, a reduction gear box, a screw-machine barrel accessory, a machine frame and a feeding bucket. The power source is connected with a screw inside the screw-machine barrel accessory through the reduction gear box. The feeding bucket communicates with a machine barrel inside the screw-machine barrel accessory. The screw is installed inside the machine barrel. Cooling and temperature-reducing device are installed at the lower part of a feeding opening of the machine barrel and at a closely adjacent section to make the two sections as cooling sections, the sections after which are provided with heating devices which make the rest sections as the heating sections. Only one vent is arranged at the machine barrel. The screw, which is installed inside the machine barrel, is the cone-shaped screw and is provided with a mixing section, and the same time the length-diameter ratio of the machine barrel and the screw is more than 30. Before the vent, the present invention can convey, compress, heat and plastify the wood-plastic composite material under the quite low temperature; after being completely plastified, the plastic can complete enwrap the heated wooden powder before the vent and mix with the wooden powder uniformly; a double-screw vacuum exhausting and flash-preventing device which continuously rotates downwards can exhaust as well as never flash.