The invention discloses a method for producing a side plate of a dump truck bed, which comprises the following steps of: machining a rolled plate into a flat plate with a required length, a required width and a required size, and along the length direction of the flat plate, longitudinally pressing the flat plate by using a cold roll forming production line to form the side plate of the bed at least with a reinforcing rib. The method has the advantages of simple operation, once molding and capability of reaching high strength without welding the reinforcing ribs on the side plate of the bed; and the cold roll forming method has the advantages of completely improving the production efficiency of the side plate of the bed, simultaneously reducing the labor intensity of workers, reducing independence on the workers, stabilizing the quality of the product and reducing power consumption and pollutions of welding fume to human bodies and the environment.