Abstract: Described here in the essay is the R & D process of the carbon steel-stainless steel seamless bimetal metallurgical composite hot bend，including details about the key manufacturing technology, property parameters, testing items and relevant standard. Also involved are the selection of the mother tube, preparation of the overall R & D plan, analysis of the critical control points, setting of the process parameters and the simulation testing, modification and upgrade of related equipment, and experiments concerning the mechanical properties and the corrosion resistance, etc. The bimetal composite bend as finally developed possesses good mechanical properties and corrosion resistance，and the hi-precession geometric dimensions of the product has been well controlled. The carbon steel layer and the stainless steel layer of the said type of bend have metallurgical bonding with a shear strength exceeding 200 MPa. In comparison with the built-up bend（i.e. overlaying the stainless steel layer on the carbon steel layer），this product has more uniform wall thickness，and the manufacturing process for such pipe features high efficiency，and small manufacturing size restrictions. Compared to the conventional explosive-clad weld composite pipe，the said hot bend can avoid problems such as serrated interface and straight welding seam，having the safety and the economy properly balanced，and met the service requirements for the high-corrosion oil and gas transportation pipeline.