Abstract: A method for manufacturing rough-surfaced plastic sheet is based on technique, using cooperative extrusion by means of two or more extrusion machines. A main extrusion machine is for forming a main body of a plastic sheet. One or two auxiliary extrusion machine are for forming one or two rough-surface layers with plastic material, pigment and processing agent, which are melted and mixed together inside to let the foaming agent in the barrel generate bubbles and explode at the same time to form the plastic into one or two rough-surfaced layers. Then, after the main body and the rough-surfaced together pass through a mold head, the rough-surfaced layer adheres to one or two outer surfaces of the main body, cooled at once to form a plastic board with one or two rough surfaces, thus heightening producing efficiency, lowering investment coat and elevating competitive force.