The invention discloses a single-screw sheet extruder. The single-screw sheet extruder comprises a machine frame, a feeding device, an exhaust type single extrusion screw, a gear pump, an extrusion die head, a glazing press, an edge pressing and dividing machine, a traction device, a drying device, a storage shelf and a winding device, wherein the exhaust type single extrusion screw successively comprises a feeding section, a first compression section, a first metering section, a mixing section, a pressure reduction section, an exhaust section, a second compression section and a second metering section from front to back. According to the single-screw sheet extruder disclosed by the invention, the exhaust type structure is adopted, and through reasonable segmentation, the material conveying capability, the plasticizing effect and the exhaust effect are effectively improved; the single-screw sheet extruder has the exhaust function, so that water in the raw materials of plastics can be vaporized and pumped during extrusion processing, the water content of the prepared material is guaranteed to conform to requirements; the raw materials do not need to be dried before being added in the extruder, so that the drying time of the raw materials can be shortened, the energy consumption is lowered, the equipment cost is reduced, and improvement of the production efficiency can be facilitated.