Abstract: To manufacture the large length-diameter ratio metallurgical composite tube，the 3-roll rotary rolling composite technology is employed to get the 304 stainless steel/20 carbon steel（304SS/20CS）metallurgical composite tube successfully produced via the axially continuous forming process. The research indicates that the composite tube as made exhibits excellent interfacial bonding performance，and that any shearing fracture only occurs on the 20CS matrix side； the interfacial shear strength increases with the rise of the rolling temperature，and reaches a peak value of 327 MPa at 1 200 ℃；and the outward diffusion of alloying elements（e.g.，Cr and Ni）from 304SS into 20CS under high-temperature condition significantly enhances the solid solution strengthening effect. Meanwhile，the increase of the elongation leads to reduction of the decarburization layer thickness in 20CS. Thanks to joint effect of these factors，the said composite tube obtains the best interfacial bonding strength at 1 200 ℃.