The bimetallic barrel for single screw extruder is a kind of barrel spray 2-5mm thick alloy coat on the barrel inner wall which has excellent corrosion resistance, abrasion resistance and high working temperature. And its useful service life is greatly improved contrast to common nitrided barrel. Bimetal has more obvious advantages when processing special plastics to enhance the abrasion life, such as engineering plastics, fluoride plastics, PPO etc. Our company use special alloy powders being sprayed and welded on the top of screw flights, and use different alloys and welding methods.