The sheet extruder is composed of extrusion, calendaring, traction and rolling. The main parts are abrasion resistant, resistant to corrosion, high-temperature resistant by high quality specially-treated. Low resistance force in die head extruding channel makes sheet thickness evenly, the internal spiral tank in three rollers ensures an effective cooling and it is easy to change and install net changer with the hydraulic pressure unit, no need to stop machine. The machine extrudes PP/PS granule to PP/PS sheet with single color, which is used for producing plastic products by plastic thermoforming machines, like cups, food container, trays, dishes, bowls, lids, etc.